Simplify the public event and CPU API

Applications now need far less ceremony: hello.c is a 20-line loop that
handles REFRESH, CLOSE and QUIT and draws into the surface's own pixels.

- Fold GEOMETRY, STATE and FOCUS into one WINDOW event carrying size,
  scale and state; unchanged values send nothing.
- Guarantee REFRESH once a window has a size and after every resize,
  never at size zero.
- Merge DROP_HOVER into DROP with over/leave/data actions and give drag
  and drop actions enums.
- Keep event strings valid until the next wait and drop
  yasl_event_release; empty or failed waits report NONE.
- Replace copy-in presentation with a lent pixel buffer:
  yasl_cpu_pixels and yasl_cpu_present.
- Remove yasl_poll_event, yasl_cpu_read_pixels, unused event fields and
  comments that restated names.
- Wayland: resize floating windows in request_size instead of reporting
  it unsupported, and stop marking new GPU surfaces as Vulkan so
  yasl_vulkan_create_surface no longer fails with NATIVE_WINDOW_IN_USE.

Also includes the in-progress public API refactor that was uncommitted
in the tree (removal of the app/loop layer, new surface, GL and Vulkan
entry points).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

5 files changed, 831 insertions, 299 deletions

diff --git a/src/platform/cocoa/api.h b/src/platform/cocoa/api.h
index eaacc01..4a22410 100644
--- a/src/platform/cocoa/api.h
+++ b/src/platform/cocoa/api.h
@@ -1,40 +1,40 @@
-#ifndef YASL_COCOA_API_H
-#define YASL_COCOA_API_H
+#ifndef YASL_PRIVATE_COCOA_API_H
+#define YASL_PRIVATE_COCOA_API_H
 
-#include "yasl/yasl.h"
+#include "common/types.h"
 
 struct cocoa_display;
 struct cocoa_surface;
 
-struct cocoa_display *cocoa_display_open(struct yasl_loop *loop, const struct yasl_display_spec *spec);
+struct cocoa_display *cocoa_display_open(struct yasl_private_loop *loop, const struct yasl_private_display_spec *spec);
 void cocoa_display_close(struct cocoa_display *d);
 uint32_t cocoa_display_caps(const struct cocoa_display *d);
 int cocoa_display_dispatch_timeout(struct cocoa_display *d, int timeout_ms);
 void cocoa_display_flush(struct cocoa_display *d);
 int cocoa_display_modifiers(const struct cocoa_display *d);
-void cocoa_display_copy(struct cocoa_display *d, enum yasl_selection sel, const char *text);
-void cocoa_display_paste(struct cocoa_display *d, enum yasl_selection sel, struct cocoa_surface *target);
-bool cocoa_display_drag_start(struct cocoa_display *d, struct cocoa_surface *origin, const struct yasl_drag_image *image, const struct yasl_drag_listener *l, void *ud);
+void cocoa_display_copy(struct cocoa_display *d, enum yasl_private_selection sel, const char *text);
+void cocoa_display_paste(struct cocoa_display *d, enum yasl_private_selection sel, struct cocoa_surface *target);
+bool cocoa_display_drag_start(struct cocoa_display *d, struct cocoa_surface *origin, const struct yasl_private_drag_image *image, const struct yasl_private_drag_listener *l, void *ud);
 struct cocoa_surface *cocoa_surface_create_toplevel(struct cocoa_display *d,
-        const struct yasl_window_spec *spec, void *graphics_device);
-struct cocoa_surface *cocoa_surface_create_popup(struct cocoa_surface *parent, const struct yasl_popup_spec *spec);
-bool cocoa_surface_popup_reposition(struct cocoa_surface *popup, const struct yasl_popup_spec *spec);
+        const struct yasl_private_window_spec *spec, void *graphics_device);
+struct cocoa_surface *cocoa_surface_create_popup(struct cocoa_surface *parent, const struct yasl_private_popup_spec *spec);
+bool cocoa_surface_popup_reposition(struct cocoa_surface *popup, const struct yasl_private_popup_spec *spec);
 void cocoa_surface_destroy(struct cocoa_surface *s);
-void cocoa_surface_set_callbacks(struct cocoa_surface *s, const struct yasl_window_cbs *cbs, void *ud);
+void cocoa_surface_set_callbacks(struct cocoa_surface *s, const struct yasl_private_window_cbs *cbs, void *ud);
 void cocoa_surface_set_title(struct cocoa_surface *s, const char *title);
 void cocoa_surface_schedule_redraw(struct cocoa_surface *s);
-bool cocoa_surface_present(struct cocoa_surface *s, const struct yasl_framebuffer *fb, const struct yasl_damage_list *damage);
-bool cocoa_surface_poll_event(struct cocoa_surface *s, struct yasl_event *ev);
-struct yasl_geometry cocoa_surface_geometry(const struct cocoa_surface *s);
-struct yasl_timing cocoa_surface_timing(const struct cocoa_surface *s);
-void cocoa_surface_set_cursor(struct cocoa_surface *s, enum yasl_cursor cursor);
+bool cocoa_surface_present(struct cocoa_surface *s, const struct yasl_private_framebuffer *fb, const struct yasl_private_damage_list *damage);
+bool cocoa_surface_poll_event(struct cocoa_surface *s, struct yasl_private_event *ev);
+struct yasl_private_geometry cocoa_surface_geometry(const struct cocoa_surface *s);
+struct yasl_private_timing cocoa_surface_timing(const struct cocoa_surface *s);
+void cocoa_surface_set_cursor(struct cocoa_surface *s, enum yasl_private_cursor cursor);
 void cocoa_surface_set_background_color(struct cocoa_surface *s, uint32_t bg);
 bool cocoa_surface_ime_preedit_cursor(const struct cocoa_surface *s, int *begin, int *end);
-void cocoa_surface_set_ime_caret(struct cocoa_surface *s, struct yasl_rect2i caret);
+void cocoa_surface_set_ime_caret(struct cocoa_surface *s, struct yasl_private_rect2i caret);
 bool cocoa_surface_start_interactive_move(struct cocoa_surface *s);
-bool cocoa_surface_start_interactive_resize(struct cocoa_surface *s, enum yasl_resize_edge edge);
-bool cocoa_surface_show_window_menu(struct cocoa_surface *s, struct yasl_vector2i pos);
-bool cocoa_surface_drag_carry(struct cocoa_surface *s, struct yasl_vector2i offset);
-bool cocoa_surface_place_under_pointer(struct cocoa_surface *s, struct yasl_vector2i at);
+bool cocoa_surface_start_interactive_resize(struct cocoa_surface *s, enum yasl_private_resize_edge edge);
+bool cocoa_surface_show_window_menu(struct cocoa_surface *s, struct yasl_private_vector2i pos);
+bool cocoa_surface_drag_carry(struct cocoa_surface *s, struct yasl_private_vector2i offset);
+bool cocoa_surface_place_under_pointer(struct cocoa_surface *s, struct yasl_private_vector2i at);
 
 #endif
diff --git a/src/platform/cocoa/desktop.m b/src/platform/cocoa/desktop.m
index 526cbb9..76aa551 100644
--- a/src/platform/cocoa/desktop.m
+++ b/src/platform/cocoa/desktop.m
@@ -2,7 +2,7 @@
 #import <UserNotifications/UserNotifications.h>
 
 #include "common/desktop.h"
-#include "yasl/desktop.h"
+#include "common/private_desktop.h"
 
 #include <CoreFoundation/CoreFoundation.h>
 #include <limits.h>
@@ -94,11 +94,11 @@ uint32_t desktop_appearance(void)
         NSAppearanceName name = [NSApp.effectiveAppearance
             bestMatchFromAppearancesWithNames:@[NSAppearanceNameAqua, NSAppearanceNameDarkAqua]];
         if ([name isEqualToString:NSAppearanceNameDarkAqua])
-            flags |= YASL_APPEARANCE_DARK;
+            flags |= YASL_PRIVATE_APPEARANCE_DARK;
         else if (name)
-            flags |= YASL_APPEARANCE_LIGHT;
+            flags |= YASL_PRIVATE_APPEARANCE_LIGHT;
         if ([NSWorkspace sharedWorkspace].accessibilityDisplayShouldIncreaseContrast)
-            flags |= YASL_APPEARANCE_HIGH_CONTRAST;
+            flags |= YASL_PRIVATE_APPEARANCE_HIGH_CONTRAST;
         return flags;
     }
 }
diff --git a/src/platform/cocoa/keymap.c b/src/platform/cocoa/keymap.c
index b81c364..c43837c 100644
--- a/src/platform/cocoa/keymap.c
+++ b/src/platform/cocoa/keymap.c
@@ -1,7 +1,7 @@
 #include "keymap.h"
 #include "keycodes.h"
 
-enum yasl_key yasl_key_from_cocoa(uint32_t code)
+enum yasl_key yasl_private_key_from_cocoa(uint32_t code)
 {
     switch (code) {
     case kVK_ANSI_A: return YASL_KEY_A;
diff --git a/src/platform/cocoa/keymap.h b/src/platform/cocoa/keymap.h
index a5394e2..792b10d 100644
--- a/src/platform/cocoa/keymap.h
+++ b/src/platform/cocoa/keymap.h
@@ -1,8 +1,8 @@
-#ifndef YASL_COCOA_KEYMAP_H
-#define YASL_COCOA_KEYMAP_H
+#ifndef YASL_PRIVATE_COCOA_KEYMAP_H
+#define YASL_PRIVATE_COCOA_KEYMAP_H
 
 #include "yasl/keycodes.h"
 
-enum yasl_key yasl_key_from_cocoa(uint32_t code);
+enum yasl_key yasl_private_key_from_cocoa(uint32_t code);
 
 #endif
diff --git a/src/platform/cocoa/window.m b/src/platform/cocoa/window.m
index 60b20b0..7be78fd 100644
--- a/src/platform/cocoa/window.m
+++ b/src/platform/cocoa/window.m
@@ -1,10 +1,12 @@
 #import <AppKit/AppKit.h>
 #import <Metal/Metal.h>
 #import <QuartzCore/QuartzCore.h>
+#import <OpenGL/OpenGL.h>
 
 #include "platform/cocoa/api.h"
 #include "common/backend.h"
-#include "yasl/native/cocoa.h"
+#include "common/public_internal.h"
+#include "common/private_native_cocoa.h"
 #include "common/timing.h"
 #include "common/loop.h"
 #include "platform/cocoa/keycodes.h"
@@ -18,8 +20,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <dlfcn.h>
 #include <sys/event.h>
 #include <unistd.h>
+#include <objc/message.h>
+#include <objc/runtime.h>
 
 #define LINK_IDLE_FRAMES 8
 /* Application-defined event subtype that only wakes a waiting dispatch. */
@@ -63,6 +68,7 @@ struct cocoa_surface {
     YaslWindowController *controller;
     YaslView *view;
     CAMetalLayer *layer;
+    NSOpenGLContext *gl_context;
     id<MTLCommandQueue> software_queue;
     id<MTLBuffer> software_buffer;
     NSUInteger software_buffer_capacity;
@@ -70,16 +76,19 @@ struct cocoa_surface {
 
     struct cocoa_surface *parent;
     bool is_popup;
-    struct yasl_vector2i content_offset;
+    struct yasl_private_vector2i content_offset;
 
-    const struct yasl_window_cbs *cbs;
+    const struct yasl_private_window_cbs *cbs;
     void *ud;
     uint64_t frames_skipped;
 
     char *preedit;
-    struct yasl_rect2i ime_caret;
+    size_t preedit_begin, preedit_end;
+    NSUInteger marked_utf16_location;
+    uint64_t preedit_revision, preedit_generation;
+    struct yasl_private_rect2i ime_caret;
 
-    struct yasl_vector2i size;
+    struct yasl_private_vector2i size;
     uint32_t scale_120;
     uint32_t bg_color;
     uint32_t *pixels;
@@ -87,11 +96,11 @@ struct cocoa_surface {
 
     id<CAMetalDrawable> drawable;
     bool transaction;
-    struct yasl_frame frame;
-    struct yasl_damage_list damage;
+    struct yasl_private_frame frame;
+    struct yasl_private_damage_list damage;
     bool did_present;
     /* Extent of the frame in pixels, valid while did_present is set. */
-    struct yasl_vector2i shown_size;
+    struct yasl_private_vector2i shown_size;
     unsigned idle_frames;
     bool want_draw;
     bool frame_due;
@@ -102,27 +111,29 @@ struct cocoa_surface {
     struct cocoa_surface *dead_next;
 
     struct input_queue input;
-    struct yasl_vector2i pointer;
+    struct yasl_private_vector2i pointer;
     double scroll_x;
     uint32_t mods;
     uint32_t buttons;
-    enum yasl_cursor cursor;
-    enum yasl_pointer_device tablet_device;
+    enum yasl_private_cursor cursor;
+    enum yasl_private_pointer_device tablet_device;
     bool tablet_down;
+    uint64_t pen_device_id, pen_tool_id;
+    uint32_t pen_buttons;
 
     char title[160];
-    struct yasl_frame_clock clock;
+    struct yasl_private_frame_clock clock;
 };
 
 struct cocoa_display {
-    struct yasl_display base;
+    struct yasl_private_display base;
     struct cocoa_surface **windows;
     int count;
     int capacity;
-    const struct yasl_display_cbs *cbs;
+    const struct yasl_private_display_cbs *cbs;
     void *ud;
     char *app_id;
-    struct yasl_loop *loop;
+    struct yasl_private_loop *loop;
     id key_up_monitor;
     NSCursor *hidden_cursor;
     YaslAppDelegate *delegate;
@@ -132,15 +143,15 @@ struct cocoa_display {
         bool active;
         struct cocoa_surface *origin;
         struct cocoa_surface *carried;
-        struct yasl_vector2i carry_offset;
+        struct yasl_private_vector2i carry_offset;
         struct cocoa_surface *hover;
-        struct yasl_vector2i hover_pos;
-        struct yasl_drag_listener listener;
+        struct yasl_private_vector2i hover_pos;
+        struct yasl_private_drag_listener listener;
         void *ud;
         NSImage *image;
         NSWindow *image_window;
-        struct yasl_vector2i image_size;
-        struct yasl_vector2i image_hotspot;
+        struct yasl_private_vector2i image_size;
+        struct yasl_private_vector2i image_hotspot;
     } drag;
     int depth;
     bool open;
@@ -151,16 +162,16 @@ struct cocoa_display {
 
 static struct cocoa_display darwin_ctx;
 
-static void drag_end(struct cocoa_display *d, enum yasl_drag_end how)
+static void drag_end(struct cocoa_display *d, enum yasl_private_drag_end how)
 {
     if (!d || !d->drag.active) return;
-    struct yasl_drag_listener l = d->drag.listener;
+    struct yasl_private_drag_listener l = d->drag.listener;
     void *ud = d->drag.ud;
     struct cocoa_surface *hover = d->drag.hover;
-    struct yasl_vector2i pos = d->drag.hover_pos;
+    struct yasl_private_vector2i pos = d->drag.hover_pos;
 
     d->drag.active = false;
-    d->drag.listener = (struct yasl_drag_listener){0};
+    d->drag.listener = (struct yasl_private_drag_listener){0};
     d->drag.hover = NULL;
     d->drag.origin = NULL;
     d->drag.carried = NULL;
@@ -175,10 +186,10 @@ static void drag_end(struct cocoa_display *d, enum yasl_drag_end how)
 
     if (hover && !hover->destroyed) {
         darwin_ctx.depth++;
-        if (how == YASL_DRAG_DROPPED)
-            yasl_surface_notify_drag(&hover->base, YASL_DRAG_DROP, pos);
+        if (how == YASL_PRIVATE_DRAG_DROPPED)
+            yasl_private_surface_notify_drag(&hover->base, YASL_PRIVATE_DRAG_DROP, pos);
         else
-            yasl_surface_notify_drag(&hover->base, YASL_DRAG_LEAVE, pos);
+            yasl_private_surface_notify_drag(&hover->base, YASL_PRIVATE_DRAG_LEAVE, pos);
         darwin_ctx.depth--;
     }
     if (l.end)
@@ -187,6 +198,7 @@ static void drag_end(struct cocoa_display *d, enum yasl_drag_end how)
 
 static void render_and_commit(struct cocoa_surface *w);
 static void reap_dead(struct cocoa_display *d);
+static void push_pen(struct cocoa_surface *w, NSEvent *event, unsigned action, bool contact);
 
 static void set_state(struct cocoa_surface *w, uint32_t bit, bool on)
 {
@@ -197,21 +209,25 @@ static void set_state(struct cocoa_surface *w, uint32_t bit, bool on)
         return;
     w->base.state = next;
     darwin_ctx.depth++;
-    yasl_surface_notify_state(&w->base, next);
+    yasl_private_surface_notify_state(&w->base, next);
     darwin_ctx.depth--;
 }
 
 static void check_pointer_reset(struct cocoa_surface *w)
 {
     if (!w || w->closed) return;
-    if (w->buttons != 0 || w->tablet_down) {
-        struct yasl_event ev = {
-            .type = YASL_EVENT_INPUT_RESET,
+    if (w->buttons != 0 || w->tablet_down || w->tablet_device != YASL_PRIVATE_PTR_DEV_MOUSE) {
+        if (w->tablet_device != YASL_PRIVATE_PTR_DEV_MOUSE)
+            push_pen(w, nil, YASL_PRIVATE_PEN_CANCEL, false);
+        struct yasl_private_event ev = {
+            .type = YASL_PRIVATE_EVENT_INPUT_RESET,
             .surface = &w->base,
         };
         input_queue_push(&w->input, &ev);
         w->buttons = 0;
         w->tablet_down = false;
+        w->tablet_device = YASL_PRIVATE_PTR_DEV_MOUSE;
+        w->pen_device_id = w->pen_tool_id = 0;
     }
 }
 
@@ -221,14 +237,14 @@ static void push_focus(struct cocoa_surface *w, bool focused)
         return;
     if (!focused)
         check_pointer_reset(w);
-    struct yasl_event ev = {
-        .type = YASL_EVENT_FOCUS,
+    struct yasl_private_event ev = {
+        .type = YASL_PRIVATE_EVENT_FOCUS,
         .surface = &w->base,
         .focus = { .focused = focused },
     };
     input_queue_push(&w->input, &ev);
     darwin_ctx.depth++;
-    set_state(w, YASL_STATE_ACTIVATED, focused);
+    set_state(w, YASL_PRIVATE_STATE_ACTIVATED, focused);
     if (!w->destroyed && !w->closed)
         cocoa_surface_schedule_redraw(w);
     darwin_ctx.depth--;
@@ -236,18 +252,18 @@ static void push_focus(struct cocoa_surface *w, bool focused)
 
 static void sync_size(struct cocoa_surface *w, bool force)
 {
-    if (!w || w->destroyed || !w->layer || w->closed)
+    if (!w || w->destroyed || w->closed || !w->view || !w->window)
         return;
-    uint64_t start = yasl_loop_now_ns();
+    uint64_t start = yasl_private_loop_now_ns();
     NSRect bounds = w->view.bounds;
     CGFloat scale = w->window.backingScaleFactor;
     if (scale < 1.0)
         scale = 1.0;
-    struct yasl_vector2i size = {
+    struct yasl_private_vector2i size = {
         .x = (int)lround(bounds.size.width * scale),
         .y = (int)lround(bounds.size.height * scale),
     };
-    uint32_t scale_120 = (uint32_t)lround(scale * YASL_SCALE_UNIT);
+    uint32_t scale_120 = (uint32_t)lround(scale * YASL_PRIVATE_SCALE_UNIT);
     bool rescaled = force || scale_120 != w->scale_120;
     bool resized = force || (size.x != w->size.x || size.y != w->size.y);
     if (!rescaled && !resized)
@@ -255,15 +271,21 @@ static void sync_size(struct cocoa_surface *w, bool force)
     darwin_ctx.depth++;
     w->size = size;
     w->scale_120 = scale_120;
-    w->layer.contentsScale = scale;
-    w->layer.drawableSize = CGSizeMake(size.x, size.y);
+    if (w->layer) {
+        w->layer.contentsScale = scale;
+        w->layer.drawableSize = CGSizeMake(size.x, size.y);
+    }
+    if (w->gl_context)
+        [w->gl_context update];
     /* Common configure notification already requests a frame before invoking
      * the legacy callback. Finish local bookkeeping before that callback can
      * destroy this surface. */
-    yasl_clock_note_resize(&w->clock, yasl_loop_now_ns() - start);
-    yasl_surface_notify_configure(&w->base, (struct yasl_geometry){
+    yasl_private_clock_note_resize(&w->clock, yasl_private_loop_now_ns() - start);
+    yasl_private_surface_notify_configure(&w->base, (struct yasl_private_geometry){
             .size = size, .scale_120 = scale_120,
         });
+    if (w->base.presenter != YASL_PRIVATE_PRESENTER_CPU)
+        yasl_private_surface_notify_refresh(&w->base);
     if (!w->destroyed && !w->closed && w->view.inLiveResize)
         render_and_commit(w);
     darwin_ctx.depth--;
@@ -272,11 +294,11 @@ static void sync_size(struct cocoa_surface *w, bool force)
 static unsigned cocoa_mods(NSEventModifierFlags m)
 {
     unsigned mods = 0;
-    if (m & NSEventModifierFlagShift) mods |= YASL_MOD_SHIFT;
-    if (m & NSEventModifierFlagOption) mods |= YASL_MOD_ALT;
-    if (m & NSEventModifierFlagControl) mods |= YASL_MOD_CTRL;
-    if (m & NSEventModifierFlagCommand) mods |= YASL_MOD_SUPER;
-    if (m & NSEventModifierFlagCapsLock) mods |= YASL_MOD_CAPS;
+    if (m & NSEventModifierFlagShift) mods |= YASL_PRIVATE_MOD_SHIFT;
+    if (m & NSEventModifierFlagOption) mods |= YASL_PRIVATE_MOD_ALT;
+    if (m & NSEventModifierFlagControl) mods |= YASL_PRIVATE_MOD_CTRL;
+    if (m & NSEventModifierFlagCommand) mods |= YASL_PRIVATE_MOD_SUPER;
+    if (m & NSEventModifierFlagCapsLock) mods |= YASL_PRIVATE_MOD_CAPS;
     return mods;
 }
 
@@ -287,19 +309,19 @@ static uint32_t cocoa_key_label(NSString *characters)
     if (!characters.length) return 0;
     unichar first = [characters characterAtIndex:0];
     if (characters.length == 1)
-        return yasl_key_label(first);
+        return yasl_private_key_label(first);
     if (characters.length == 2 && first >= 0xd800 && first <= 0xdbff) {
         unichar second = [characters characterAtIndex:1];
         if (second >= 0xdc00 && second <= 0xdfff)
-            return yasl_key_label(0x10000 + ((first - 0xd800) << 10) + second - 0xdc00);
+            return yasl_private_key_label(0x10000 + ((first - 0xd800) << 10) + second - 0xdc00);
     }
     return 0;
 }
 
-static struct yasl_key_event cocoa_key_event(NSEvent *ev, enum yasl_key_action action)
+static struct yasl_private_key_event cocoa_key_event(NSEvent *ev, enum yasl_key_action action)
 {
-    struct yasl_key_event k = {
-        .key = yasl_key_from_cocoa(ev.keyCode),
+    struct yasl_private_key_event k = {
+        .key = yasl_private_key_from_cocoa(ev.keyCode),
         .action = action,
         .mods = cocoa_mods(ev.modifierFlags),
         .native_code = ev.keyCode,
@@ -315,27 +337,15 @@ static struct yasl_key_event cocoa_key_event(NSEvent *ev, enum yasl_key_action a
 static void on_key_event(struct cocoa_surface *w, NSEvent *ev, enum yasl_key_action action)
 {
     w->mods = cocoa_mods(ev.modifierFlags);
-    struct yasl_key_event k = cocoa_key_event(ev, action);
-    struct yasl_event input_ev = {
-        .type = YASL_EVENT_KEY,
+    struct yasl_private_key_event k = cocoa_key_event(ev, action);
+    struct yasl_private_event input_ev = {
+        .type = YASL_PRIVATE_EVENT_KEY,
         .surface = &w->base,
         .key = k,
     };
     input_queue_push(&w->input, &input_ev);
 }
 
-static void on_text_input(struct cocoa_surface *w, const char *text, size_t len)
-{
-    if (len) {
-        struct yasl_event ev = {
-            .type = YASL_EVENT_TEXT,
-            .surface = &w->base,
-            .text = { .data = text, .len = len },
-        };
-        input_queue_push(&w->input, &ev);
-    }
-}
-
 static bool modifier_down(NSEvent *ev)
 {
     NSEventModifierFlags f = ev.modifierFlags;
@@ -356,22 +366,22 @@ static bool modifier_down(NSEvent *ev)
 static int cocoa_button(NSInteger number)
 {
     switch (number) {
-    case 0: return YASL_BUTTON_PRIMARY;
-    case 1: return YASL_BUTTON_SECONDARY;
-    case 2: return YASL_BUTTON_MIDDLE;
-    case 3: return YASL_BUTTON_BACK;
-    case 4: return YASL_BUTTON_FORWARD;
+    case 0: return YASL_PRIVATE_BUTTON_PRIMARY;
+    case 1: return YASL_PRIVATE_BUTTON_SECONDARY;
+    case 2: return YASL_PRIVATE_BUTTON_MIDDLE;
+    case 3: return YASL_PRIVATE_BUTTON_BACK;
+    case 4: return YASL_PRIVATE_BUTTON_FORWARD;
     default: return -1;
     }
 }
 
-static struct yasl_vector2i event_pos(struct cocoa_surface *w, NSEvent *ev)
+static struct yasl_private_vector2i event_pos(struct cocoa_surface *w, NSEvent *ev)
 {
     NSPoint p = [w->view convertPoint:ev.locationInWindow fromView:nil];
     CGFloat scale = w->window.backingScaleFactor;
     if (scale < 1.0)
         scale = 1.0;
-    return (struct yasl_vector2i){
+    return (struct yasl_private_vector2i){
         .x = (int)floor(p.x * scale),
         .y = (int)floor((w->view.bounds.size.height - p.y) * scale),
     };
@@ -389,7 +399,7 @@ static void update_drag_hover(struct cocoa_display *d, NSPoint screenPoint)
 
     NSInteger winNum = [NSWindow windowNumberAtPoint:screenPoint belowWindowWithWindowNumber:excludeNum];
     struct cocoa_surface *target = NULL;
-    struct yasl_vector2i pos = {0};
+    struct yasl_private_vector2i pos = {0};
 
     if (winNum > 0) {
         NSWindow *nswin = [NSApp windowWithWindowNumber:winNum];
@@ -429,11 +439,11 @@ static void update_drag_hover(struct cocoa_display *d, NSPoint screenPoint)
     if (target != d->drag.hover) {
         if (d->drag.hover) {
             struct cocoa_surface *old = d->drag.hover;
-            struct yasl_vector2i old_pos = d->drag.hover_pos;
+            struct yasl_private_vector2i old_pos = d->drag.hover_pos;
             d->drag.hover = NULL;
             if (!old->destroyed) {
                 darwin_ctx.depth++;
-                yasl_surface_notify_drag(&old->base, YASL_DRAG_LEAVE, old_pos);
+                yasl_private_surface_notify_drag(&old->base, YASL_PRIVATE_DRAG_LEAVE, old_pos);
                 darwin_ctx.depth--;
             }
             if (!d->drag.active) return;
@@ -443,23 +453,117 @@ static void update_drag_hover(struct cocoa_display *d, NSPoint screenPoint)
         d->drag.hover_pos = pos;
         if (target && !target->destroyed) {
             darwin_ctx.depth++;
-            yasl_surface_notify_drag(&target->base, YASL_DRAG_OVER, pos);
+            yasl_private_surface_notify_drag(&target->base, YASL_PRIVATE_DRAG_OVER, pos);
             darwin_ctx.depth--;
         }
     } else if (target && !target->destroyed) {
         d->drag.hover_pos = pos;
         darwin_ctx.depth++;
-        yasl_surface_notify_drag(&target->base, YASL_DRAG_OVER, pos);
+        yasl_private_surface_notify_drag(&target->base, YASL_PRIVATE_DRAG_OVER, pos);
         darwin_ctx.depth--;
     }
 }
 
-static void push_pointer(struct cocoa_surface *w, NSEvent *ev, enum yasl_event_type type,
+static uint64_t event_integer(NSEvent *event, const char *name)
+{
+    SEL selector = sel_registerName(name);
+    if (![event respondsToSelector:selector]) return 0;
+    return (uint64_t)((NSInteger (*)(id, SEL))objc_msgSend)(event, selector);
+}
+
+static double event_double(NSEvent *event, const char *name)
+{
+    SEL selector = sel_registerName(name);
+    if (![event respondsToSelector:selector]) return 0;
+    return ((double (*)(id, SEL))objc_msgSend)(event, selector);
+}
+
+static void push_pen(struct cocoa_surface *w, NSEvent *event, unsigned action, bool contact)
+{
+    if (!w || w->closed || w->tablet_device == YASL_PRIVATE_PTR_DEV_MOUSE) return;
+    struct yasl_private_pen_sample pen = {
+        .device_id = w->pen_device_id,
+        .tool_id = w->pen_tool_id,
+        .x = w->pointer.x,
+        .y = w->pointer.y,
+        .tool = w->tablet_device == YASL_PRIVATE_PTR_DEV_ERASER ? 2u : 1u,
+        .action = action,
+        .in_contact = contact,
+    };
+    if (event) {
+        if (w->view && [event respondsToSelector:@selector(locationInWindow)]) {
+            NSPoint point = [w->view convertPoint:event.locationInWindow fromView:nil];
+            CGFloat scale = w->window.backingScaleFactor;
+            if (scale < 1.0) scale = 1.0;
+            pen.x = point.x * scale;
+            pen.y = (w->view.bounds.size.height - point.y) * scale;
+        }
+        if (event.buttonMask & NSEventButtonMaskPenTip)
+            pen.buttons |= YASL_PRIVATE_BUTTON_BIT(YASL_PRIVATE_BUTTON_PRIMARY);
+        if (event.buttonMask & NSEventButtonMaskPenLowerSide)
+            pen.buttons |= YASL_PRIVATE_BUTTON_BIT(YASL_PRIVATE_BUTTON_SECONDARY);
+        if (event.buttonMask & NSEventButtonMaskPenUpperSide)
+            pen.buttons |= YASL_PRIVATE_BUTTON_BIT(YASL_PRIVATE_BUTTON_MIDDLE);
+        if (event.type == NSEventTypeTabletPoint || event.subtype == NSEventSubtypeTabletPoint) {
+            pen.pressure = fmax(0.0, fmin(1.0, event.pressure));
+            pen.axes_valid |= YASL_PRIVATE_PEN_PRESSURE;
+            pen.axes_changed |= YASL_PRIVATE_PEN_PRESSURE;
+            NSPoint tilt = event.tilt;
+            pen.tilt_x = fmax(-90.0, fmin(90.0, tilt.x * 90.0));
+            pen.tilt_y = fmax(-90.0, fmin(90.0, -tilt.y * 90.0));
+            pen.axes_valid |= YASL_PRIVATE_PEN_TILT;
+            pen.axes_changed |= YASL_PRIVATE_PEN_TILT;
+            if ([event respondsToSelector:@selector(rotation)]) {
+                pen.rotation = event_double(event, "rotation");
+                pen.axes_valid |= YASL_PRIVATE_PEN_ROTATION;
+                pen.axes_changed |= YASL_PRIVATE_PEN_ROTATION;
+            }
+            if ([event respondsToSelector:@selector(tangentialPressure)]) {
+                pen.tangential = event_double(event, "tangentialPressure");
+                pen.axes_valid |= YASL_PRIVATE_PEN_TANGENTIAL;
+                pen.axes_changed |= YASL_PRIVATE_PEN_TANGENTIAL;
+            }
+        }
+        uint64_t device = event_integer(event, "pointingDeviceID");
+        uint64_t tool = event_integer(event, "pointingDeviceSerialNumber");
+        if (device) pen.device_id = device;
+        if (tool) pen.tool_id = tool;
+    }
+    if (action == YASL_PRIVATE_PEN_DOWN) {
+        pen.buttons |= YASL_PRIVATE_BUTTON_BIT(YASL_PRIVATE_BUTTON_PRIMARY);
+        pen.changed_button = YASL_PRIVATE_BUTTON_BIT(YASL_PRIVATE_BUTTON_PRIMARY);
+    } else if (action == YASL_PRIVATE_PEN_UP) {
+        pen.buttons &= ~YASL_PRIVATE_BUTTON_BIT(YASL_PRIVATE_BUTTON_PRIMARY);
+        pen.changed_button = YASL_PRIVATE_BUTTON_BIT(YASL_PRIVATE_BUTTON_PRIMARY);
+    }
+    if (action == YASL_PRIVATE_PEN_LEAVE || action == YASL_PRIVATE_PEN_CANCEL) {
+        pen.buttons = 0;
+        pen.in_contact = false;
+        pen.pressure = 0;
+        w->pen_buttons = 0;
+    } else {
+        uint32_t changed = pen.buttons ^ w->pen_buttons;
+        if (action == YASL_PRIVATE_PEN_MOVE && changed) {
+            action = YASL_PRIVATE_PEN_BUTTON;
+            pen.changed_button = changed & (~changed + 1u);
+        }
+        w->pen_buttons = pen.buttons;
+    }
+    pen.action = action;
+    struct yasl_private_event ev = {
+        .type = YASL_PRIVATE_EVENT_PEN,
+        .surface = &w->base,
+        .pen = pen,
+    };
+    input_queue_push(&w->input, &ev);
+}
+
+static void push_pointer(struct cocoa_surface *w, NSEvent *ev, enum yasl_private_event_type type,
                          int button)
 {
     if (!w || w->closed)
         return;
-    if ((type == YASL_EVENT_POINTER_DOWN || type == YASL_EVENT_POINTER_UP) &&
+    if ((type == YASL_PRIVATE_EVENT_POINTER_DOWN || type == YASL_PRIVATE_EVENT_POINTER_UP) &&
         (button < 0 || button > 4))
         return;
     bool proximity = ev.type == NSEventTypeTabletProximity ||
@@ -467,26 +571,30 @@ static void push_pointer(struct cocoa_surface *w, NSEvent *ev, enum yasl_event_t
     if (proximity) {
         if (ev.isEnteringProximity) {
             w->tablet_device = ev.pointingDeviceType == NSPointingDeviceTypeEraser ?
-                YASL_PTR_DEV_ERASER : ev.pointingDeviceType == NSPointingDeviceTypePen ?
-                YASL_PTR_DEV_PEN : YASL_PTR_DEV_MOUSE;
+                YASL_PRIVATE_PTR_DEV_ERASER : ev.pointingDeviceType == NSPointingDeviceTypePen ?
+                YASL_PRIVATE_PTR_DEV_PEN : YASL_PRIVATE_PTR_DEV_MOUSE;
+            w->pen_device_id = event_integer(ev, "pointingDeviceID");
+            w->pen_tool_id = event_integer(ev, "pointingDeviceSerialNumber");
+            if (w->tablet_device != YASL_PRIVATE_PTR_DEV_MOUSE)
+                push_pen(w, ev, YASL_PRIVATE_PEN_ENTER, false);
             return;
         }
-        type = YASL_EVENT_POINTER_LEAVE;
+        type = YASL_PRIVATE_EVENT_POINTER_LEAVE;
     }
     w->mods = cocoa_mods(ev.modifierFlags);
-    if (type != YASL_EVENT_POINTER_LEAVE)
+    if (type != YASL_PRIVATE_EVENT_POINTER_LEAVE)
         w->pointer = event_pos(w, ev);
 
-    enum yasl_pointer_device device = YASL_PTR_DEV_MOUSE;
-    struct yasl_pointer_pen pen = {0};
+    enum yasl_private_pointer_device device = YASL_PRIVATE_PTR_DEV_MOUSE;
+    struct yasl_private_pointer_pen pen = {0};
 
-    if (type == YASL_EVENT_POINTER_LEAVE && w->tablet_device != YASL_PTR_DEV_MOUSE) {
+    if (type == YASL_PRIVATE_EVENT_POINTER_LEAVE && w->tablet_device != YASL_PRIVATE_PTR_DEV_MOUSE) {
         device = w->tablet_device;
         w->tablet_down = false;
     } else if (ev.type == NSEventTypeTabletPoint || ev.subtype == NSEventSubtypeTabletPoint) {
         /* pointingDeviceType belongs to proximity events. Remember that
          * event's tool so erasers and zero-pressure hover stay classified. */
-        device = w->tablet_device == YASL_PTR_DEV_ERASER ? YASL_PTR_DEV_ERASER : YASL_PTR_DEV_PEN;
+        device = w->tablet_device == YASL_PRIVATE_PTR_DEV_ERASER ? YASL_PRIVATE_PTR_DEV_ERASER : YASL_PRIVATE_PTR_DEV_PEN;
         float press = (float)ev.pressure;
         if (press > 1.0f) press = 1.0f;
         if (press > 0.0f)
@@ -495,32 +603,40 @@ static void push_pointer(struct cocoa_surface *w, NSEvent *ev, enum yasl_event_t
         NSPoint tilt = ev.tilt;
         pen.tilt_x = (int8_t)lround(fmax(-1, fmin(1, tilt.x)) * 90.0);
         pen.tilt_y = (int8_t)lround(fmax(-1, fmin(1, -tilt.y)) * 90.0);
-        if (button == 0 && type == YASL_EVENT_POINTER_DOWN) w->tablet_down = true;
-        if (button == 0 && type == YASL_EVENT_POINTER_UP) {
+        if (button == 0 && type == YASL_PRIVATE_EVENT_POINTER_DOWN) w->tablet_down = true;
+        if (button == 0 && type == YASL_PRIVATE_EVENT_POINTER_UP) {
             w->tablet_down = false;
             pen.pressure = 0;
         }
     }
 
-    if (type == YASL_EVENT_POINTER_DOWN && button >= 0 && button < 32)
+    if (type == YASL_PRIVATE_EVENT_POINTER_DOWN && button >= 0 && button < 32)
         w->buttons |= (1u << button);
-    else if (type == YASL_EVENT_POINTER_UP && button >= 0 && button < 32)
+    else if (type == YASL_PRIVATE_EVENT_POINTER_UP && button >= 0 && button < 32)
         w->buttons &= ~(1u << button);
 
-    struct yasl_event input_ev = {
+    struct yasl_private_event input_ev = {
         .type = type,
         .surface = &w->base,
         .pointer = {
             .pos = w->pointer,
-            .button = (type == YASL_EVENT_POINTER_DOWN || type == YASL_EVENT_POINTER_UP) ?
-                      (enum yasl_pointer_button)button : YASL_BUTTON_PRIMARY,
+            .button = (type == YASL_PRIVATE_EVENT_POINTER_DOWN || type == YASL_PRIVATE_EVENT_POINTER_UP) ?
+                      (enum yasl_private_pointer_button)button : YASL_PRIVATE_BUTTON_PRIMARY,
             .device = device,
             .mods = w->mods,
             .pen = pen,
         },
     };
     input_queue_push(&w->input, &input_ev);
-    if (type == YASL_EVENT_POINTER_MOTION && darwin_ctx.drag.active) {
+    if (type == YASL_PRIVATE_EVENT_POINTER_LEAVE && device != YASL_PRIVATE_PTR_DEV_MOUSE) {
+        push_pen(w, ev, YASL_PRIVATE_PEN_LEAVE, false);
+    } else if (ev.type == NSEventTypeTabletPoint || ev.subtype == NSEventSubtypeTabletPoint) {
+        unsigned action = button == YASL_PRIVATE_BUTTON_PRIMARY && type == YASL_PRIVATE_EVENT_POINTER_DOWN ? YASL_PRIVATE_PEN_DOWN :
+            button == YASL_PRIVATE_BUTTON_PRIMARY && type == YASL_PRIVATE_EVENT_POINTER_UP ? YASL_PRIVATE_PEN_UP :
+            YASL_PRIVATE_PEN_MOVE;
+        push_pen(w, ev, action, w->tablet_down);
+    }
+    if (type == YASL_PRIVATE_EVENT_POINTER_MOTION && darwin_ctx.drag.active) {
         if (darwin_ctx.drag.carried) {
             cocoa_surface_place_under_pointer(darwin_ctx.drag.carried, darwin_ctx.drag.carry_offset);
         } else if (darwin_ctx.drag.image_window) {
@@ -534,23 +650,24 @@ static void push_pointer(struct cocoa_surface *w, NSEvent *ev, enum yasl_event_t
                 mouse.y - pt_h + darwin_ctx.drag.image_hotspot.y / scale)];
         }
         update_drag_hover(&darwin_ctx, [NSEvent mouseLocation]);
-    } else if (type == YASL_EVENT_POINTER_UP && darwin_ctx.drag.active) {
+    } else if (type == YASL_PRIVATE_EVENT_POINTER_UP && darwin_ctx.drag.active) {
         update_drag_hover(&darwin_ctx, [NSEvent mouseLocation]);
-        drag_end(&darwin_ctx, YASL_DRAG_DROPPED);
+        drag_end(&darwin_ctx, YASL_PRIVATE_DRAG_DROPPED);
     }
     if (proximity) {
-        w->tablet_device = YASL_PTR_DEV_MOUSE;
+        w->tablet_device = YASL_PRIVATE_PTR_DEV_MOUSE;
         w->tablet_down = false;
+        w->pen_device_id = w->pen_tool_id = 0;
     }
 }
 
-static NSCursor *cocoa_cursor(enum yasl_cursor cursor)
+static NSCursor *cocoa_cursor(enum yasl_private_cursor cursor)
 {
     switch (cursor) {
-    case YASL_CURSOR_TEXT: return [NSCursor IBeamCursor];
-    case YASL_CURSOR_LINK: return [NSCursor pointingHandCursor];
-    case YASL_CURSOR_CROSSHAIR: return [NSCursor crosshairCursor];
-    case YASL_CURSOR_HIDDEN:
+    case YASL_PRIVATE_CURSOR_TEXT: return [NSCursor IBeamCursor];
+    case YASL_PRIVATE_CURSOR_LINK: return [NSCursor pointingHandCursor];
+    case YASL_PRIVATE_CURSOR_CROSSHAIR: return [NSCursor crosshairCursor];
+    case YASL_PRIVATE_CURSOR_HIDDEN:
         if (!darwin_ctx.hidden_cursor) {
             NSImage *image = [[NSImage alloc] initWithSize:NSMakeSize(1, 1)];
             [image lockFocus];
@@ -561,7 +678,7 @@ static NSCursor *cocoa_cursor(enum yasl_cursor cursor)
             [image release];
         }
         return darwin_ctx.hidden_cursor;
-    case YASL_CURSOR_ARROW:
+    case YASL_PRIVATE_CURSOR_ARROW:
     default: return [NSCursor arrowCursor];
     }
 }
@@ -570,14 +687,14 @@ static NSCursor *cocoa_cursor(enum yasl_cursor cursor)
 - (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender
 {
     (void)sender;
-    yasl_display_notify_event(&darwin_ctx.base, YASL_EVENT_DISPLAY_QUIT);
+    yasl_private_display_notify_event(&darwin_ctx.base, YASL_PRIVATE_EVENT_DISPLAY_QUIT);
     return NSTerminateCancel;
 }
 - (BOOL)applicationShouldHandleReopen:(NSApplication *)sender hasVisibleWindows:(BOOL)visible
 {
     (void)sender;
     if (!visible)
-        yasl_display_notify_event(&darwin_ctx.base, YASL_EVENT_DISPLAY_REOPEN);
+        yasl_private_display_notify_event(&darwin_ctx.base, YASL_PRIVATE_EVENT_DISPLAY_REOPEN);
     return YES;
 }
 - (BOOL)applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)sender
@@ -587,13 +704,13 @@ static NSCursor *cocoa_cursor(enum yasl_cursor cursor)
 }
 @end
 
-static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> sender)
+static struct yasl_private_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> sender)
 {
     NSPoint p = [view convertPoint:[sender draggingLocation] fromView:nil];
     NSWindow *win = view.window;
     CGFloat scale = win ? win.backingScaleFactor : 1.0;
     if (scale < 1.0) scale = 1.0;
-    return (struct yasl_vector2i){
+    return (struct yasl_private_vector2i){
         .x = (int)floor(p.x * scale),
         .y = (int)floor((view.bounds.size.height - p.y) * scale),
     };
@@ -619,9 +736,9 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
     if ([pb canReadItemWithDataConformingToTypes:@[NSPasteboardTypeFileURL]]) {
         struct cocoa_surface *w = self.surface;
         if (w && !w->closed) {
-            struct yasl_vector2i pos = dragging_pos(self, sender);
+            struct yasl_private_vector2i pos = dragging_pos(self, sender);
             darwin_ctx.depth++;
-            yasl_surface_notify_drop(&w->base, YASL_DROP_OVER, pos);
+            yasl_private_surface_notify_drop(&w->base, YASL_PRIVATE_DROP_OVER, pos);
             darwin_ctx.depth--;
         }
         return NSDragOperationCopy;
@@ -640,9 +757,9 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
     if ([pb canReadItemWithDataConformingToTypes:@[NSPasteboardTypeFileURL]]) {
         struct cocoa_surface *w = self.surface;
         if (w && !w->closed) {
-            struct yasl_vector2i pos = dragging_pos(self, sender);
+            struct yasl_private_vector2i pos = dragging_pos(self, sender);
             darwin_ctx.depth++;
-            yasl_surface_notify_drop(&w->base, YASL_DROP_LEAVE, pos);
+            yasl_private_surface_notify_drop(&w->base, YASL_PRIVATE_DROP_LEAVE, pos);
             darwin_ctx.depth--;
         }
     }
@@ -652,7 +769,7 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
 {
     struct cocoa_surface *w = self.surface;
     if (!w) return NO;
-    struct yasl_vector2i pos = dragging_pos(self, sender);
+    struct yasl_private_vector2i pos = dragging_pos(self, sender);
     BOOL ok = NO;
 
     NSPasteboard *pb = [sender draggingPasteboard];
@@ -666,8 +783,8 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
         }
         const char *utf8 = result.UTF8String;
         if (utf8 && strlen(utf8)) {
-            struct yasl_event ev = {
-                .type = YASL_EVENT_DROP,
+            struct yasl_private_event ev = {
+                .type = YASL_PRIVATE_EVENT_DROP,
                 .surface = &w->base,
                 .text = { .data = utf8, .len = strlen(utf8) },
             };
@@ -678,7 +795,7 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
     }
     if (!w->destroyed) {
         darwin_ctx.depth++;
-        yasl_surface_notify_drop(&w->base, YASL_DROP_LEAVE, pos);
+        yasl_private_surface_notify_drop(&w->base, YASL_PRIVATE_DROP_LEAVE, pos);
         darwin_ctx.depth--;
     }
     return ok;
@@ -704,6 +821,13 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
 - (BOOL)canBecomeKeyView { return YES; }
 - (BOOL)wantsUpdateLayer { return YES; }
 
+- (void)updateLayer
+{
+    struct cocoa_surface *w = self.surface;
+    if (w && !w->closed && w->base.presenter != YASL_PRIVATE_PRESENTER_CPU)
+        yasl_private_surface_notify_refresh(&w->base);
+}
+
 - (void)setFrameSize:(NSSize)size
 {
     [super setFrameSize:size];
@@ -743,14 +867,14 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
     if (period > 0.0 && period < 0.25)
         w->clock.refresh_ns = period * 1e9;
     w->frame_due = true;
-    if (!w->want_draw || (w->base.state & YASL_STATE_SUSPENDED)) {
+    if (!w->want_draw || (w->base.state & YASL_PRIVATE_STATE_SUSPENDED)) {
         if (++w->idle_frames >= LINK_IDLE_FRAMES)
             link.paused = YES;
         return;
     }
     w->idle_frames = 0;
     if (darwin_ctx.loop)
-        yasl_loop_kick(darwin_ctx.loop);
+        yasl_private_loop_kick(darwin_ctx.loop);
 }
 
 - (void)updateTrackingAreas
@@ -773,7 +897,7 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
 {
     (void)event;
     struct cocoa_surface *w = self.surface;
-    [cocoa_cursor(w ? w->cursor : YASL_CURSOR_ARROW) set];
+    [cocoa_cursor(w ? w->cursor : YASL_PRIVATE_CURSOR_ARROW) set];
 }
 
 - (void)keyDown:(NSEvent *)event
@@ -802,44 +926,44 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
 - (void)mouseDown:(NSEvent *)event
 {
     [self.window makeFirstResponder:self];
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_DOWN, cocoa_button(event.buttonNumber));
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_DOWN, cocoa_button(event.buttonNumber));
 }
 - (void)rightMouseDown:(NSEvent *)event { [self mouseDown:event]; }
 - (void)otherMouseDown:(NSEvent *)event { [self mouseDown:event]; }
 
 - (void)mouseUp:(NSEvent *)event
 {
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_UP, cocoa_button(event.buttonNumber));
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_UP, cocoa_button(event.buttonNumber));
 }
 - (void)rightMouseUp:(NSEvent *)event { [self mouseUp:event]; }
 - (void)otherMouseUp:(NSEvent *)event { [self mouseUp:event]; }
 
 - (void)mouseMoved:(NSEvent *)event
 {
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_MOTION, 0);
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_MOTION, 0);
 }
 
 - (void)mouseDragged:(NSEvent *)event
 {
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_MOTION, 0);
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_MOTION, 0);
 }
 - (void)rightMouseDragged:(NSEvent *)event
 {
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_MOTION, 0);
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_MOTION, 0);
 }
 - (void)otherMouseDragged:(NSEvent *)event
 {
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_MOTION, 0);
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_MOTION, 0);
 }
 
 - (void)mouseExited:(NSEvent *)event
 {
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_LEAVE, 0);
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_LEAVE, 0);
 }
 
 - (void)tabletProximity:(NSEvent *)event
 {
-    push_pointer(self.surface, event, YASL_EVENT_POINTER_MOTION, 0);
+    push_pointer(self.surface, event, YASL_PRIVATE_EVENT_POINTER_MOTION, 0);
 }
 
 - (void)tabletPoint:(NSEvent *)event
@@ -847,8 +971,8 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
     struct cocoa_surface *w = self.surface;
     if (!w) return;
     bool down = (event.buttonMask & NSEventButtonMaskPenTip) != 0;
-    enum yasl_event_type type = down == w->tablet_down ? YASL_EVENT_POINTER_MOTION :
-        down ? YASL_EVENT_POINTER_DOWN : YASL_EVENT_POINTER_UP;
+    enum yasl_private_event_type type = down == w->tablet_down ? YASL_PRIVATE_EVENT_POINTER_MOTION :
+        down ? YASL_PRIVATE_EVENT_POINTER_DOWN : YASL_PRIVATE_EVENT_POINTER_UP;
     push_pointer(w, event, type, 0);
 }
 
@@ -864,8 +988,8 @@ static struct yasl_vector2i dragging_pos(YaslView *view, id<NSDraggingInfo> send
     if (!isfinite(dx) || !isfinite(dy) || (dx == 0 && dy == 0)) return;
     w->mods = cocoa_mods(event.modifierFlags);
     w->pointer = event_pos(w, event);
-    struct yasl_event input_ev = {
-        .type = YASL_EVENT_POINTER_SCROLL,
+    struct yasl_private_event input_ev = {
+        .type = YASL_PRIVATE_EVENT_POINTER_SCROLL,
         .surface = &w->base,
         .pointer = {
             .pos = w->pointer,
@@ -882,34 +1006,131 @@ static NSString *plain_string(id string)
         ? [(NSAttributedString *)string string] : (NSString *)string;
 }
 
+static bool text_utf16_to_utf8(NSString *text, NSUInteger index, size_t *byte_offset)
+{
+    if (!text || index > text.length) return false;
+    const char *prefix = [[text substringToIndex:index] UTF8String];
+    if (!prefix) return false;
+    *byte_offset = strlen(prefix);
+    return true;
+}
+
+static bool text_utf8_to_utf16(const char *text, size_t byte_offset, NSUInteger *index)
+{
+    size_t len = text ? strlen(text) : 0;
+    if (byte_offset > len) return false;
+    NSString *prefix = [[NSString alloc] initWithBytes:text length:byte_offset
+                                              encoding:NSUTF8StringEncoding];
+    if (!prefix) return false;
+    *index = prefix.length;
+    [prefix release];
+    return true;
+}
+
+static bool text_edit_range(struct cocoa_surface *w, NSRange range, bool use_marked,
+                            size_t *begin, size_t *end)
+{
+    if (range.location == NSNotFound) {
+        if (use_marked && w->preedit) {
+            if (w->preedit_revision != w->base.text_revision ||
+                w->preedit_generation != w->base.text_generation)
+                return false;
+            *begin = w->preedit_begin;
+            *end = w->preedit_end;
+        } else {
+            *begin = w->base.text_begin;
+            *end = w->base.text_end;
+        }
+        return *begin <= *end && *end <= w->base.text_length;
+    }
+    NSString *surrounding = [NSString stringWithUTF8String:w->base.text_surrounding ?: ""];
+    size_t a, b;
+    if (!surrounding || range.location > surrounding.length ||
+        range.length > surrounding.length - range.location ||
+        !text_utf16_to_utf8(surrounding, range.location, &a) ||
+        !text_utf16_to_utf8(surrounding, range.location + range.length, &b))
+        return false;
+    *begin = a;
+    *end = b;
+    return true;
+}
+
+static void push_text_edit(struct cocoa_surface *w, const char *text, size_t len,
+                           size_t begin, size_t end)
+{
+    if (!w->base.text_input_active || begin > end || end > w->base.text_length) return;
+    struct yasl_private_event ev = {
+        .type = YASL_PRIVATE_EVENT_TEXT_EDIT,
+        .surface = &w->base,
+        .text_edit = {
+            .data = text ?: "", .len = len,
+            .revision = w->base.text_revision,
+            .generation = w->base.text_generation,
+            .begin = begin, .end = end,
+        },
+    };
+    input_queue_push(&w->input, &ev);
+}
+
 - (void)insertText:(id)string replacementRange:(NSRange)replacementRange
 {
-    (void)replacementRange;
     struct cocoa_surface *w = self.surface;
-    if (!w || w->destroyed || w->closed) return;
+    if (!w || w->destroyed || w->closed || !w->base.text_input_active) return;
     const char *utf8 = plain_string(string).UTF8String;
     size_t len = utf8 ? strlen(utf8) : 0;
+    size_t begin, end;
+    if (!text_edit_range(w, replacementRange, true, &begin, &end)) return;
     bool had_preedit = w->preedit != NULL;
+    darwin_ctx.depth++;
+    push_text_edit(w, utf8, len, begin, end);
     free(w->preedit);
     w->preedit = NULL;
-    darwin_ctx.depth++;
-    on_text_input(w, utf8, len);
+    w->preedit_begin = w->preedit_end = 0;
     if (had_preedit)
-        yasl_surface_notify_composition(&w->base, NULL, -1, -1);
+        yasl_private_surface_notify_composition(&w->base, NULL, -1, -1);
     if (!w->destroyed && !w->closed)
         cocoa_surface_schedule_redraw(w);
     darwin_ctx.depth--;
 }
 
-- (void)doCommandBySelector:(SEL)selector { (void)selector; }
+- (void)doCommandBySelector:(SEL)selector
+{
+    struct cocoa_surface *w = self.surface;
+    if (!w || w->destroyed || w->closed || !w->base.text_input_active) return;
+    NSString *surrounding = [NSString stringWithUTF8String:w->base.text_surrounding ?: ""];
+    NSUInteger begin, end;
+    if (!sel_isEqual(selector, @selector(deleteBackward)) &&
+        !sel_isEqual(selector, @selector(deleteForward))) return;
+    if (!text_utf8_to_utf16(w->base.text_surrounding ?: "", w->base.text_begin, &begin) ||
+        !text_utf8_to_utf16(w->base.text_surrounding ?: "", w->base.text_end, &end)) return;
+    if (begin == end && sel_isEqual(selector, @selector(deleteBackward)) && begin > 0) {
+        NSRange composed = [surrounding rangeOfComposedCharacterSequenceAtIndex:begin - 1];
+        begin = composed.location;
+    } else if (begin == end && sel_isEqual(selector, @selector(deleteForward)) && end < surrounding.length) {
+        NSRange composed = [surrounding rangeOfComposedCharacterSequenceAtIndex:end];
+        end = NSMaxRange(composed);
+    }
+    size_t byte_begin, byte_end;
+    if (text_utf16_to_utf8(surrounding, begin, &byte_begin) &&
+        text_utf16_to_utf8(surrounding, end, &byte_end) && byte_begin != byte_end)
+        push_text_edit(w, "", 0, byte_begin, byte_end);
+}
 
 - (void)setMarkedText:(id)string selectedRange:(NSRange)selectedRange
      replacementRange:(NSRange)replacementRange
 {
-    (void)replacementRange;
     struct cocoa_surface *w = self.surface;
-    if (!w || w->destroyed || w->closed) return;
+    if (!w || w->destroyed || w->closed || !w->base.text_input_active) return;
     NSString *str = plain_string(string);
+    size_t range_begin, range_end;
+    if (!text_edit_range(w, replacementRange, true, &range_begin, &range_end)) return;
+    w->preedit_begin = range_begin;
+    w->preedit_end = range_end;
+    w->preedit_revision = w->base.text_revision;
+    w->preedit_generation = w->base.text_generation;
+    if (!text_utf8_to_utf16(w->base.text_surrounding ?: "", range_begin,
+                            &w->marked_utf16_location))
+        w->marked_utf16_location = 0;
     const char *utf8 = str.length ? str.UTF8String : NULL;
     free(w->preedit);
     w->preedit = utf8 ? strdup(utf8) : NULL;
@@ -926,7 +1147,7 @@ static NSString *plain_string(id string)
         }
     }
     darwin_ctx.depth++;
-    yasl_surface_notify_composition(&w->base, w->preedit, begin, end);
+    yasl_private_surface_notify_composition(&w->base, w->preedit, begin, end);
     if (!w->destroyed && !w->closed)
         cocoa_surface_schedule_redraw(w);
     darwin_ctx.depth--;
@@ -939,19 +1160,28 @@ static NSString *plain_string(id string)
     free(w->preedit);
     w->preedit = NULL;
     darwin_ctx.depth++;
-    yasl_surface_notify_composition(&w->base, NULL, -1, -1);
+    yasl_private_surface_notify_composition(&w->base, NULL, -1, -1);
     if (!w->destroyed && !w->closed)
         cocoa_surface_schedule_redraw(w);
     darwin_ctx.depth--;
 }
 
-- (NSRange)selectedRange { return NSMakeRange(NSNotFound, 0); }
+- (NSRange)selectedRange
+{
+    struct cocoa_surface *w = self.surface;
+    if (!w || !w->base.text_input_active) return NSMakeRange(NSNotFound, 0);
+    NSUInteger begin, end;
+    if (!text_utf8_to_utf16(w->base.text_surrounding ?: "", w->base.text_begin, &begin) ||
+        !text_utf8_to_utf16(w->base.text_surrounding ?: "", w->base.text_end, &end))
+        return NSMakeRange(NSNotFound, 0);
+    return NSMakeRange(begin, end - begin);
+}
 - (NSRange)markedRange
 {
     struct cocoa_surface *w = self.surface;
     if (!w || !w->preedit)
         return NSMakeRange(NSNotFound, 0);
-    return NSMakeRange(0, [NSString stringWithUTF8String:w->preedit].length);
+    return NSMakeRange(w->marked_utf16_location, [NSString stringWithUTF8String:w->preedit].length);
 }
 - (BOOL)hasMarkedText { return self.surface && self.surface->preedit != NULL; }
 - (nullable NSAttributedString *)attributedSubstringForProposedRange:(NSRange)range
@@ -1012,7 +1242,7 @@ static NSString *plain_string(id string)
     if (!w) return;
     bool visible = (self.window.occlusionState & NSWindowOcclusionStateVisible) != 0;
     darwin_ctx.depth++;
-    set_state(w, YASL_STATE_SUSPENDED, !visible);
+    set_state(w, YASL_PRIVATE_STATE_SUSPENDED, !visible);
     if (!w->destroyed && !w->closed) {
         if (visible)
             cocoa_surface_schedule_redraw(w);
@@ -1042,8 +1272,8 @@ static NSString *plain_string(id string)
         return;
     darwin_ctx.depth++;
     bool fullscreen = (self.window.styleMask & NSWindowStyleMaskFullScreen) != 0;
-    set_state(w, YASL_STATE_FULLSCREEN, fullscreen);
-    set_state(w, YASL_STATE_MAXIMIZED, !fullscreen && self.window.isZoomed);
+    set_state(w, YASL_PRIVATE_STATE_FULLSCREEN, fullscreen);
+    set_state(w, YASL_PRIVATE_STATE_MAXIMIZED, !fullscreen && self.window.isZoomed);
     sync_size(w, false);
     darwin_ctx.depth--;
 }
@@ -1075,16 +1305,16 @@ static NSString *plain_string(id string)
     darwin_ctx.depth++;
     w->closed = true;
     [w->link invalidate];
-    yasl_surface_notify_close(&w->base);
+    yasl_private_surface_notify_close(&w->base);
     darwin_ctx.depth--;
 }
 
 @end
 
-bool cocoa_surface_present(struct cocoa_surface *w, const struct yasl_framebuffer *fb,
-                          const struct yasl_damage_list *damage)
+bool cocoa_surface_present(struct cocoa_surface *w, const struct yasl_private_framebuffer *fb,
+                          const struct yasl_private_damage_list *damage)
 {
-    if (!w || w->closed || !w->rendering || w->did_present || !fb || !damage ||
+    if (!w || w->base.presenter != YASL_PRIVATE_PRESENTER_CPU || w->closed || !w->rendering || w->did_present || !fb || !damage ||
         fb->pixels != w->frame.target.pixels || fb->size.x != w->size.x ||
         fb->size.y != w->size.y || !w->drawable)
         return false;
@@ -1116,7 +1346,7 @@ bool cocoa_surface_present(struct cocoa_surface *w, const struct yasl_framebuffe
         [command presentDrawable:drawable];
         [command commit];
     }
-    yasl_clock_presented(&w->clock, yasl_loop_now_ns(), false);
+    yasl_private_clock_presented(&w->clock, yasl_private_loop_now_ns(), false);
     w->did_present = true;
     w->shown_size = w->size;
     return true;
@@ -1124,8 +1354,8 @@ bool cocoa_surface_present(struct cocoa_surface *w, const struct yasl_framebuffe
 
 static void render_and_commit(struct cocoa_surface *w)
 {
-    if (w->destroyed || w->closed || !w->cbs->draw || w->rendering || w->size.x <= 0 || w->size.y <= 0 ||
-        (w->base.state & YASL_STATE_SUSPENDED))
+    if (w->base.presenter != YASL_PRIVATE_PRESENTER_CPU || w->destroyed || w->closed || !w->cbs->draw || w->rendering || w->size.x <= 0 || w->size.y <= 0 ||
+        (w->base.state & YASL_PRIVATE_STATE_SUSPENDED))
         return;
 
     size_t count = (size_t)w->size.x * (size_t)w->size.y;
@@ -1143,17 +1373,17 @@ static void render_and_commit(struct cocoa_surface *w)
     id<CAMetalDrawable> drawable = [w->layer nextDrawable];
     w->drawable = drawable;
     w->transaction = w->layer.presentsWithTransaction;
-    w->damage = (struct yasl_damage_list){0};
-    w->frame = (struct yasl_frame){
+    w->damage = (struct yasl_private_damage_list){0};
+    w->frame = (struct yasl_private_frame){
         .surface = &w->base,
         .target = {
-            .generation = yasl_frame_begin(&w->base),
+            .generation = yasl_private_frame_begin(&w->base),
             .pixels = w->software_queue ? w->pixels : NULL,
             .size = w->size,
         },
     };
     if (drawable)
-        yasl_surface_draw(&w->base, &w->frame);
+        yasl_private_surface_draw(&w->base, &w->frame);
     if (!w->destroyed && !w->closed && !w->did_present) {
         w->want_draw = true;
         w->frames_skipped++;
@@ -1191,7 +1421,7 @@ static void loop_ready(CFFileDescriptorRef fd, CFOptionFlags flags, void *info)
 
 /* A kqueue mirroring the loop's poll set, or -1. complete is false when some
  * descriptor could not be registered. */
-static int loop_kqueue(struct yasl_loop *loop, bool *complete)
+static int loop_kqueue(struct yasl_private_loop *loop, bool *complete)
 {
     *complete = true;
     int kq = kqueue();
@@ -1200,7 +1430,7 @@ static int loop_kqueue(struct yasl_loop *loop, bool *complete)
         return -1;
     }
     const struct pollfd *fds;
-    int n = yasl_loop_poll_set(loop, &fds);
+    int n = yasl_private_loop_poll_set(loop, &fds);
     for (int i = 0; i < n; i++) {
         struct kevent change;
         if (fds[i].events & POLLIN) {
@@ -1238,7 +1468,7 @@ int cocoa_display_dispatch_timeout(struct cocoa_display *d, int timeout_ms)
     int count = 0;
     @try {
         if (d->loop) {
-            int timer_to = yasl_loop_next_timeout_ms(d->loop);
+            int timer_to = yasl_private_loop_next_timeout_ms(d->loop);
             if (timer_to >= 0 && (timeout_ms < 0 || timer_to < timeout_ms)) {
                 timeout_ms = timer_to;
             }
@@ -1303,7 +1533,7 @@ int cocoa_display_dispatch_timeout(struct cocoa_display *d, int timeout_ms)
         }
 
         if (d->loop) {
-            yasl_loop_step(d->loop, 0);
+            yasl_private_loop_step(d->loop, 0);
         }
     } @finally {
         d->depth--;
@@ -1331,6 +1561,10 @@ void cocoa_display_flush(struct cocoa_display *d)
 void cocoa_surface_schedule_redraw(struct cocoa_surface *w)
 {
     if (!w || w->closed) return;
+    if (w->base.presenter != YASL_PRIVATE_PRESENTER_CPU) {
+        yasl_private_surface_notify_refresh(&w->base);
+        return;
+    }
     w->want_draw = true;
     w->idle_frames = 0;
     if (w->link.paused) {
@@ -1338,7 +1572,7 @@ void cocoa_surface_schedule_redraw(struct cocoa_surface *w)
         w->link.paused = NO;
     }
     if (darwin_ctx.loop)
-        yasl_loop_kick(darwin_ctx.loop);
+        yasl_private_loop_kick(darwin_ctx.loop);
 }
 
 static void app_init(const char *app_name)
@@ -1390,17 +1624,17 @@ static void place_window(NSWindow *window)
     darwin_ctx.cascade = [window cascadeTopLeftFromPoint:darwin_ctx.cascade];
 }
 
-struct cocoa_display *cocoa_display_open(struct yasl_loop *loop, const struct yasl_display_spec *spec)
+struct cocoa_display *cocoa_display_open(struct yasl_private_loop *loop, const struct yasl_private_display_spec *spec)
 {
     assert([NSThread isMainThread]);
     if (darwin_ctx.open) return NULL;
     const char *name = spec && spec->app_id ? spec->app_id : "YASL";
     @autoreleasepool { app_init(name); }
-    darwin_ctx.base.ops = &yasl_cocoa_backend;
+    darwin_ctx.base.ops = &yasl_private_cocoa_backend;
     darwin_ctx.base.native_handle = (__bridge void *)[NSApplication sharedApplication];
     darwin_ctx.open = true;
     if (!loop) {
-        darwin_ctx.loop = yasl_loop_create();
+        darwin_ctx.loop = yasl_private_loop_create();
         darwin_ctx.owns_loop = true;
     } else {
         darwin_ctx.loop = loop;
@@ -1408,7 +1642,7 @@ struct cocoa_display *cocoa_display_open(struct yasl_loop *loop, const struct ya
     }
     darwin_ctx.base.loop = darwin_ctx.loop;
     if (spec) {
-        darwin_ctx.base.callbacks = spec->cbs ? *spec->cbs : (struct yasl_display_cbs){0};
+        darwin_ctx.base.callbacks = spec->cbs ? *spec->cbs : (struct yasl_private_display_cbs){0};
         darwin_ctx.cbs = &darwin_ctx.base.callbacks;
         darwin_ctx.ud = spec->ud;
         darwin_ctx.base.callback_ud = spec->ud;
@@ -1421,7 +1655,7 @@ struct cocoa_display *cocoa_display_open(struct yasl_loop *loop, const struct ya
 void cocoa_display_close(struct cocoa_display *d)
 {
     if (!d) return;
-    drag_end(d, YASL_DRAG_CANCELLED);
+    drag_end(d, YASL_PRIVATE_DRAG_CANCELLED);
     assert(!d->count && "destroy every surface before its display");
     reap_dead(d);
     if (d->key_up_monitor) {
@@ -1429,7 +1663,7 @@ void cocoa_display_close(struct cocoa_display *d)
         d->key_up_monitor = nil;
     }
     if (d->owns_loop && d->loop) {
-        yasl_loop_destroy(d->loop);
+        yasl_private_loop_destroy(d->loop);
         d->loop = NULL;
         d->base.loop = NULL;
     }
@@ -1444,14 +1678,15 @@ void cocoa_display_close(struct cocoa_display *d)
 
 uint32_t cocoa_display_caps(const struct cocoa_display *d)
 {
-    return d ? (YASL_CAP_POPUPS | YASL_CAP_DRAG | YASL_CAP_DRAG_CARRY |
-                YASL_CAP_PLACE_WINDOW | YASL_CAP_PRIMARY_SELECTION |
-                YASL_CAP_CSD | YASL_CAP_NATIVE_GRAPHICS |
-                YASL_CAP_FRAME_PACING | YASL_CAP_TABLET) : 0;
+    return d ? (YASL_PRIVATE_CAP_POPUPS | YASL_PRIVATE_CAP_DRAG | YASL_PRIVATE_CAP_DRAG_CARRY |
+                YASL_PRIVATE_CAP_PLACE_WINDOW | YASL_PRIVATE_CAP_PRIMARY_SELECTION |
+                YASL_PRIVATE_CAP_CSD | YASL_PRIVATE_CAP_NATIVE_GRAPHICS |
+                YASL_PRIVATE_CAP_FRAME_PACING | YASL_PRIVATE_CAP_TABLET |
+                YASL_PRIVATE_CAP_TEXT_INPUT) : 0;
 }
 
 struct cocoa_surface *cocoa_surface_create_toplevel(struct cocoa_display *d,
-                                                  const struct yasl_window_spec *spec, void *graphics_device)
+                                                  const struct yasl_private_window_spec *spec, void *graphics_device)
 {
     assert([NSThread isMainThread]);
     if (!d || !d->open || !spec)
@@ -1468,15 +1703,24 @@ struct cocoa_surface *cocoa_surface_create_toplevel(struct cocoa_display *d,
         struct cocoa_surface *w = calloc(1, sizeof(*w));
         if (!w) return NULL;
         w->base.display = &d->base;
+        w->base.creation_flags = spec->flags;
+        bool external_gpu = spec->external_gpu || graphics_device != NULL;
+        /* Leave an external-GPU surface unclaimed until the public bridge
+         * selects Metal or Vulkan. Both bridges request the layer while the
+         * presenter is still NONE. */
+        w->base.presenter = external_gpu ? YASL_PRIVATE_PRESENTER_NONE : YASL_PRIVATE_PRESENTER_CPU;
         cocoa_surface_set_callbacks(w, NULL, NULL);
-        w->clock.refresh_ns = YASL_REFRESH_DEFAULT_NS;
+        w->clock.refresh_ns = YASL_PRIVATE_REFRESH_DEFAULT_NS;
         const char *t = spec->title ? spec->title : "YASL";
         strncpy(w->title, t, sizeof(w->title) - 1);
 
         int win_w = spec->size.x > 0 ? spec->size.x : 800;
         int win_h = spec->size.y > 0 ? spec->size.y : 480;
-        NSWindowStyleMask style = NSWindowStyleMaskTitled | NSWindowStyleMaskClosable |
-                                  NSWindowStyleMaskMiniaturizable | NSWindowStyleMaskResizable;
+        NSWindowStyleMask style = (spec->flags & YASL_PRIVATE_SURFACE_UNDECORATED) ?
+            NSWindowStyleMaskBorderless : NSWindowStyleMaskTitled | NSWindowStyleMaskClosable |
+                NSWindowStyleMaskMiniaturizable;
+        if (!(spec->flags & (YASL_PRIVATE_SURFACE_UNDECORATED | YASL_PRIVATE_SURFACE_FIXED_SIZE)))
+            style |= NSWindowStyleMaskResizable;
         w->window = [[YaslWindow alloc] initWithContentRect:NSMakeRect(0, 0, win_w, win_h)
                                                   styleMask:style
                                                     backing:NSBackingStoreBuffered
@@ -1499,7 +1743,7 @@ struct cocoa_surface *cocoa_surface_create_toplevel(struct cocoa_display *d,
         w->layer = (CAMetalLayer *)w->view.layer;
         if (graphics_device) {
             w->layer.device = (id<MTLDevice>)graphics_device;
-        } else {
+        } else if (!external_gpu) {
             id<MTLDevice> device = MTLCreateSystemDefaultDevice();
             w->layer.device = device;
             w->software_queue = [device newCommandQueue];
@@ -1526,13 +1770,14 @@ struct cocoa_surface *cocoa_surface_create_toplevel(struct cocoa_display *d,
         w->view.surface = w;
         darwin_ctx.windows[darwin_ctx.count++] = w;
 
-        [w->window makeKeyAndOrderFront:nil];
-        [w->window makeFirstResponder:w->view];
-        [NSApp activate];
+        if (!(spec->flags & YASL_PRIVATE_SURFACE_HIDDEN)) {
+            [w->window makeKeyAndOrderFront:nil];
+            [w->window makeFirstResponder:w->view];
+        }
 
         sync_size(w, true);
         if (spec->tearing) {
-            w->layer.displaySyncEnabled = NO;
+            if (w->layer) w->layer.displaySyncEnabled = NO;
             w->unpaced = true;
         }
         if (spec->fullscreen)
@@ -1544,6 +1789,7 @@ struct cocoa_surface *cocoa_surface_create_toplevel(struct cocoa_display *d,
 static void surface_free(struct cocoa_surface *w)
 {
     [w->link release];
+    [w->gl_context release];
     [w->software_buffer release];
     [w->software_queue release];
     [w->view release];
@@ -1570,7 +1816,7 @@ void cocoa_surface_destroy(struct cocoa_surface *w)
     if (!w || w->destroyed) return;
     if (darwin_ctx.drag.active) {
         if (darwin_ctx.drag.origin == w || darwin_ctx.drag.carried == w)
-            drag_end(&darwin_ctx, YASL_DRAG_CANCELLED);
+            drag_end(&darwin_ctx, YASL_PRIVATE_DRAG_CANCELLED);
         else if (darwin_ctx.drag.hover == w)
             darwin_ctx.drag.hover = NULL;
     }
@@ -1589,7 +1835,7 @@ void cocoa_surface_destroy(struct cocoa_surface *w)
     w->tablet_down = false;
     darwin_ctx.depth++;
     bool native_closed = w->closed;
-    static const struct yasl_window_cbs no_callbacks = {0};
+    static const struct yasl_private_window_cbs no_callbacks = {0};
     w->destroyed = true;
     w->closed = true;
     w->cbs = &no_callbacks;
@@ -1619,7 +1865,7 @@ void cocoa_surface_destroy(struct cocoa_surface *w)
     }
     darwin_ctx.depth--;
     if (darwin_ctx.loop)
-        yasl_loop_kick(darwin_ctx.loop);
+        yasl_private_loop_kick(darwin_ctx.loop);
 }
 
 void cocoa_surface_set_title(struct cocoa_surface *w, const char *title)
@@ -1629,7 +1875,7 @@ void cocoa_surface_set_title(struct cocoa_surface *w, const char *title)
     w->window.title = [NSString stringWithUTF8String:w->title] ?: @"YASL";
 }
 
-static bool impl_surface_set_size(struct yasl_surface *surface, struct yasl_vector2i size)
+static bool impl_surface_set_size(struct yasl_surface *surface, struct yasl_private_vector2i size)
 {
     struct cocoa_surface *w = (struct cocoa_surface *)surface;
     if (!w || w->closed || w->is_popup || size.x <= 0 || size.y <= 0) {
@@ -1693,16 +1939,16 @@ void cocoa_surface_set_background_color(struct cocoa_surface *w, uint32_t bg)
         dark ? NSAppearanceNameDarkAqua : NSAppearanceNameAqua];
 }
 
-void cocoa_surface_set_cursor(struct cocoa_surface *w, enum yasl_cursor cursor)
+void cocoa_surface_set_cursor(struct cocoa_surface *w, enum yasl_private_cursor cursor)
 {
-    if (!w || w->closed || cursor == w->cursor || (unsigned)cursor > YASL_CURSOR_HIDDEN) return;
+    if (!w || w->closed || cursor == w->cursor || (unsigned)cursor > YASL_PRIVATE_CURSOR_HIDDEN) return;
     w->cursor = cursor;
     NSPoint p = [w->view convertPoint:w->window.mouseLocationOutsideOfEventStream fromView:nil];
     if (w->window.isKeyWindow && NSPointInRect(p, w->view.bounds))
         [cocoa_cursor(cursor) set];
 }
 
-bool cocoa_surface_place_under_pointer(struct cocoa_surface *w, struct yasl_vector2i at)
+bool cocoa_surface_place_under_pointer(struct cocoa_surface *w, struct yasl_private_vector2i at)
 {
     if (!w || w->closed || !w->window) return false;
     CGFloat scale = w->window.backingScaleFactor;
@@ -1716,7 +1962,7 @@ bool cocoa_surface_place_under_pointer(struct cocoa_surface *w, struct yasl_vect
     return true;
 }
 
-void cocoa_surface_set_ime_caret(struct cocoa_surface *w, struct yasl_rect2i caret)
+void cocoa_surface_set_ime_caret(struct cocoa_surface *w, struct yasl_private_rect2i caret)
 {
     if (w) w->ime_caret = caret;
 }
@@ -1727,26 +1973,26 @@ bool cocoa_surface_ime_preedit_cursor(const struct cocoa_surface *w, int *begin,
     return false;
 }
 
-static NSPasteboard *pasteboard_for_selection(enum yasl_selection sel)
+static NSPasteboard *pasteboard_for_selection(enum yasl_private_selection sel)
 {
     switch (sel) {
-    case YASL_CLIPBOARD:
+    case YASL_PRIVATE_CLIPBOARD:
         return [NSPasteboard generalPasteboard];
-    case YASL_PRIMARY:
+    case YASL_PRIVATE_PRIMARY:
         return [NSPasteboard pasteboardWithName:@"dev.wsap.yasl.primary"];
     default:
         return nil;
     }
 }
 
-static bool cocoa_display_copy_text(struct cocoa_display *d, enum yasl_selection sel, const char *text);
+static bool cocoa_display_copy_text(struct cocoa_display *d, enum yasl_private_selection sel, const char *text);
 
-void cocoa_display_copy(struct cocoa_display *d, enum yasl_selection sel, const char *text)
+void cocoa_display_copy(struct cocoa_display *d, enum yasl_private_selection sel, const char *text)
 {
     (void)cocoa_display_copy_text(d, sel, text);
 }
 
-static bool cocoa_display_copy_text(struct cocoa_display *d, enum yasl_selection sel, const char *text)
+static bool cocoa_display_copy_text(struct cocoa_display *d, enum yasl_private_selection sel, const char *text)
 {
     assert([NSThread isMainThread]);
     if (!d || !text) { errno = EINVAL; return false; }
@@ -1763,7 +2009,7 @@ static bool cocoa_display_copy_text(struct cocoa_display *d, enum yasl_selection
     return true;
 }
 
-static bool cocoa_display_request_paste(struct cocoa_display *d, enum yasl_selection sel,
+static bool cocoa_display_request_paste(struct cocoa_display *d, enum yasl_private_selection sel,
                                         struct cocoa_surface *target, uint64_t id)
 {
     assert([NSThread isMainThread]);
@@ -1776,15 +2022,15 @@ static bool cocoa_display_request_paste(struct cocoa_display *d, enum yasl_selec
     if (!pb) { errno = EINVAL; return false; }
     NSString *s = [pb stringForType:NSPasteboardTypeString];
     const char *utf8 = s ? s.UTF8String : NULL;
-    enum yasl_transfer_status status = !s ? YASL_TRANSFER_UNAVAILABLE :
-        utf8 ? YASL_TRANSFER_OK : YASL_TRANSFER_FAILED;
-    yasl_surface_complete_paste(&target->base, id, status,
+    enum yasl_private_transfer_status status = !s ? YASL_PRIVATE_TRANSFER_UNAVAILABLE :
+        utf8 ? YASL_PRIVATE_TRANSFER_OK : YASL_PRIVATE_TRANSFER_FAILED;
+    yasl_private_surface_complete_paste(&target->base, id, status,
                                 utf8 ? utf8 : NULL, utf8 ? strlen(utf8) : 0);
     errno = 0;
     return true;
 }
 
-void cocoa_display_paste(struct cocoa_display *d, enum yasl_selection sel, struct cocoa_surface *target)
+void cocoa_display_paste(struct cocoa_display *d, enum yasl_private_selection sel, struct cocoa_surface *target)
 {
     (void)cocoa_display_request_paste(d, sel, target, 0);
 }
@@ -1795,18 +2041,20 @@ int cocoa_display_modifiers(const struct cocoa_display *d)
     return (int)cocoa_mods(NSEvent.modifierFlags);
 }
 
-struct yasl_geometry cocoa_surface_geometry(const struct cocoa_surface *w)
+struct yasl_private_geometry cocoa_surface_geometry(const struct cocoa_surface *w)
 {
-    return (struct yasl_geometry){
-        .size = w ? w->size : (struct yasl_vector2i){0},
-        .scale_120 = w ? w->scale_120 : YASL_SCALE_UNIT,
+    return (struct yasl_private_geometry){
+        .size = w ? w->size : (struct yasl_private_vector2i){0},
+        .scale_120 = w ? w->scale_120 : YASL_PRIVATE_SCALE_UNIT,
     };
 }
 
 static bool popup_spec_valid(const struct cocoa_surface *parent,
-                             const struct yasl_popup_spec *spec)
+                             const struct yasl_private_popup_spec *spec)
 {
     if (!parent || !spec) return false;
+    if (spec->positioner_explicit && (spec->anchor_edges > 8 || spec->gravity > 8 ||
+            (spec->constraints & ~63u))) return false;
     int parent_cx = parent->is_popup ? parent->content_offset.x : 0;
     int parent_cy = parent->is_popup ? parent->content_offset.y : 0;
     int64_t x = (int64_t)spec->anchor.x - parent_cx;
@@ -1821,7 +2069,7 @@ static bool popup_spec_valid(const struct cocoa_surface *parent,
            (int64_t)spec->content_offset.y + spec->content_size.y <= spec->size.y;
 }
 
-static NSRect popup_calc_frame(struct cocoa_surface *parent, const struct yasl_popup_spec *spec)
+static NSRect popup_calc_frame_legacy(struct cocoa_surface *parent, const struct yasl_private_popup_spec *spec)
 {
     CGFloat scale = parent->window ? parent->window.backingScaleFactor : 1.0;
     if (scale < 1.0) scale = 1.0;
@@ -1885,8 +2133,153 @@ static NSRect popup_calc_frame(struct cocoa_surface *parent, const struct yasl_p
     return frame;
 }
 
+enum {
+    POPUP_EDGE_TOP = 1,
+    POPUP_EDGE_BOTTOM = 2,
+    POPUP_EDGE_LEFT = 3,
+    POPUP_EDGE_RIGHT = 4,
+    POPUP_EDGE_TOP_LEFT = 5,
+    POPUP_EDGE_BOTTOM_LEFT = 6,
+    POPUP_EDGE_TOP_RIGHT = 7,
+    POPUP_EDGE_BOTTOM_RIGHT = 8,
+    POPUP_CONSTRAINT_SLIDE_X = 1u << 0,
+    POPUP_CONSTRAINT_SLIDE_Y = 1u << 1,
+    POPUP_CONSTRAINT_FLIP_X = 1u << 2,
+    POPUP_CONSTRAINT_FLIP_Y = 1u << 3,
+    POPUP_CONSTRAINT_RESIZE_X = 1u << 4,
+    POPUP_CONSTRAINT_RESIZE_Y = 1u << 5,
+};
+
+static bool popup_edge_has_left(unsigned edge)
+{ return edge == POPUP_EDGE_LEFT || edge == POPUP_EDGE_TOP_LEFT || edge == POPUP_EDGE_BOTTOM_LEFT; }
+static bool popup_edge_has_right(unsigned edge)
+{ return edge == POPUP_EDGE_RIGHT || edge == POPUP_EDGE_TOP_RIGHT || edge == POPUP_EDGE_BOTTOM_RIGHT; }
+static bool popup_edge_has_top(unsigned edge)
+{ return edge == POPUP_EDGE_TOP || edge == POPUP_EDGE_TOP_LEFT || edge == POPUP_EDGE_TOP_RIGHT; }
+static bool popup_edge_has_bottom(unsigned edge)
+{ return edge == POPUP_EDGE_BOTTOM || edge == POPUP_EDGE_BOTTOM_LEFT || edge == POPUP_EDGE_BOTTOM_RIGHT; }
+
+static unsigned popup_flip_x_edge(unsigned edge)
+{
+    switch (edge) {
+    case POPUP_EDGE_LEFT: return POPUP_EDGE_RIGHT;
+    case POPUP_EDGE_RIGHT: return POPUP_EDGE_LEFT;
+    case POPUP_EDGE_TOP_LEFT: return POPUP_EDGE_TOP_RIGHT;
+    case POPUP_EDGE_BOTTOM_LEFT: return POPUP_EDGE_BOTTOM_RIGHT;
+    case POPUP_EDGE_TOP_RIGHT: return POPUP_EDGE_TOP_LEFT;
+    case POPUP_EDGE_BOTTOM_RIGHT: return POPUP_EDGE_BOTTOM_LEFT;
+    default: return edge;
+    }
+}
+
+static unsigned popup_flip_y_edge(unsigned edge)
+{
+    switch (edge) {
+    case POPUP_EDGE_TOP: return POPUP_EDGE_BOTTOM;
+    case POPUP_EDGE_BOTTOM: return POPUP_EDGE_TOP;
+    case POPUP_EDGE_TOP_LEFT: return POPUP_EDGE_BOTTOM_LEFT;
+    case POPUP_EDGE_TOP_RIGHT: return POPUP_EDGE_BOTTOM_RIGHT;
+    case POPUP_EDGE_BOTTOM_LEFT: return POPUP_EDGE_TOP_LEFT;
+    case POPUP_EDGE_BOTTOM_RIGHT: return POPUP_EDGE_TOP_RIGHT;
+    default: return edge;
+    }
+}
+
+static CGFloat popup_axis_overflow(CGFloat min, CGFloat max, CGFloat visible_min, CGFloat visible_max)
+{
+    return MAX(0, visible_min - min) + MAX(0, max - visible_max);
+}
+
+static NSRect popup_frame_explicit(struct cocoa_surface *parent,
+        const struct yasl_private_popup_spec *spec, unsigned anchor, unsigned gravity)
+{
+    CGFloat scale = parent->window.backingScaleFactor;
+    if (scale < 1.0) scale = 1.0;
+    CGFloat parent_x = (parent->is_popup ? parent->content_offset.x : 0) / scale;
+    CGFloat parent_y = (parent->is_popup ? parent->content_offset.y : 0) / scale;
+    CGFloat ax = spec->anchor.x / scale - parent_x;
+    CGFloat ay = spec->anchor.y / scale - parent_y;
+    CGFloat aw = spec->anchor.width / scale;
+    CGFloat ah = spec->anchor.height / scale;
+    CGFloat anchor_x = popup_edge_has_left(anchor) ? ax :
+                       popup_edge_has_right(anchor) ? ax + aw : ax + aw * 0.5;
+    CGFloat anchor_y = popup_edge_has_top(anchor) ? ay :
+                       popup_edge_has_bottom(anchor) ? ay + ah : ay + ah * 0.5;
+    CGFloat offset_x = spec->content_offset.x / scale;
+    CGFloat offset_y = spec->content_offset.y / scale;
+    CGFloat content_w = (spec->content_size.x ? spec->content_size.x : spec->size.x - spec->content_offset.x) / scale;
+    CGFloat content_h = (spec->content_size.y ? spec->content_size.y : spec->size.y - spec->content_offset.y) / scale;
+    CGFloat content_left = popup_edge_has_right(gravity) ? anchor_x :
+                           popup_edge_has_left(gravity) ? anchor_x - content_w : anchor_x - content_w * 0.5;
+    CGFloat content_top = popup_edge_has_bottom(gravity) ? anchor_y :
+                          popup_edge_has_top(gravity) ? anchor_y - content_h : anchor_y - content_h * 0.5;
+    CGFloat top_left_x = content_left - offset_x;
+    CGFloat top_left_y = content_top - offset_y;
+
+    CGFloat view_h = parent->view.bounds.size.height;
+    NSPoint in_view = NSMakePoint(top_left_x, view_h - top_left_y);
+    NSPoint in_window = [parent->view convertPoint:in_view toView:nil];
+    NSPoint screen_top_left = [parent->window convertPointToScreen:in_window];
+    CGFloat width = spec->size.x / scale;
+    CGFloat height = spec->size.y / scale;
+    return NSMakeRect(screen_top_left.x, screen_top_left.y - height, width, height);
+}
+
+static NSRect popup_calc_frame(struct cocoa_surface *parent, const struct yasl_private_popup_spec *spec)
+{
+    if (!spec->positioner_explicit)
+        return popup_calc_frame_legacy(parent, spec);
+
+    NSRect frame = popup_frame_explicit(parent, spec, spec->anchor_edges, spec->gravity);
+    NSScreen *screen = parent->window.screen ?: [NSScreen mainScreen];
+    if (!screen) return frame;
+    NSRect visible = screen.visibleFrame;
+    unsigned constraints = spec->constraints;
+
+    if (constraints & POPUP_CONSTRAINT_FLIP_X) {
+        NSRect flipped = popup_frame_explicit(parent, spec,
+            popup_flip_x_edge(spec->anchor_edges), popup_flip_x_edge(spec->gravity));
+        if (popup_axis_overflow(flipped.origin.x, NSMaxX(flipped), NSMinX(visible), NSMaxX(visible)) <
+            popup_axis_overflow(frame.origin.x, NSMaxX(frame), NSMinX(visible), NSMaxX(visible)))
+            frame = NSMakeRect(flipped.origin.x, frame.origin.y, flipped.size.width, frame.size.height);
+    }
+    if (constraints & POPUP_CONSTRAINT_FLIP_Y) {
+        NSRect flipped = popup_frame_explicit(parent, spec,
+            popup_flip_y_edge(spec->anchor_edges), popup_flip_y_edge(spec->gravity));
+        if (popup_axis_overflow(flipped.origin.y, NSMaxY(flipped), NSMinY(visible), NSMaxY(visible)) <
+            popup_axis_overflow(frame.origin.y, NSMaxY(frame), NSMinY(visible), NSMaxY(visible)))
+            frame = NSMakeRect(frame.origin.x, flipped.origin.y, frame.size.width, flipped.size.height);
+    }
+
+    if (constraints & POPUP_CONSTRAINT_SLIDE_X) {
+        if (NSMinX(frame) < NSMinX(visible)) frame.origin.x = NSMinX(visible);
+        if (NSMaxX(frame) > NSMaxX(visible)) frame.origin.x = NSMaxX(visible) - frame.size.width;
+    }
+    if (constraints & POPUP_CONSTRAINT_SLIDE_Y) {
+        if (NSMinY(frame) < NSMinY(visible)) frame.origin.y = NSMinY(visible);
+        if (NSMaxY(frame) > NSMaxY(visible)) frame.origin.y = NSMaxY(visible) - frame.size.height;
+    }
+    if (constraints & POPUP_CONSTRAINT_RESIZE_X) {
+        if (NSMinX(frame) < NSMinX(visible)) {
+            frame.size.width = MAX(0, frame.size.width - (NSMinX(visible) - NSMinX(frame)));
+            frame.origin.x = NSMinX(visible);
+        }
+        if (NSMaxX(frame) > NSMaxX(visible))
+            frame.size.width = MAX(0, NSMaxX(visible) - frame.origin.x);
+    }
+    if (constraints & POPUP_CONSTRAINT_RESIZE_Y) {
+        if (NSMinY(frame) < NSMinY(visible)) {
+            frame.size.height = MAX(0, frame.size.height - (NSMinY(visible) - NSMinY(frame)));
+            frame.origin.y = NSMinY(visible);
+        }
+        if (NSMaxY(frame) > NSMaxY(visible))
+            frame.size.height = MAX(0, NSMaxY(visible) - frame.origin.y);
+    }
+    return frame;
+}
+
 struct cocoa_surface *cocoa_surface_create_popup(struct cocoa_surface *parent,
-        const struct yasl_popup_spec *spec)
+        const struct yasl_private_popup_spec *spec)
 {
     assert([NSThread isMainThread]);
     if (!parent || parent->closed || !parent->window || !parent->view ||
@@ -1905,8 +2298,10 @@ struct cocoa_surface *cocoa_surface_create_popup(struct cocoa_surface *parent,
         struct cocoa_surface *w = calloc(1, sizeof(*w));
         if (!w) return NULL;
         w->base.display = parent->base.display;
+        w->base.presenter = parent->base.presenter;
+        w->base.creation_flags = parent->base.creation_flags;
         cocoa_surface_set_callbacks(w, NULL, NULL);
-        w->clock.refresh_ns = parent->clock.refresh_ns ? parent->clock.refresh_ns : YASL_REFRESH_DEFAULT_NS;
+        w->clock.refresh_ns = parent->clock.refresh_ns ? parent->clock.refresh_ns : YASL_PRIVATE_REFRESH_DEFAULT_NS;
         w->parent = parent;
         w->is_popup = true;
         w->content_offset = spec->content_offset;
@@ -1968,7 +2363,7 @@ struct cocoa_surface *cocoa_surface_create_popup(struct cocoa_surface *parent,
 }
 
 bool cocoa_surface_popup_reposition(struct cocoa_surface *popup,
-        const struct yasl_popup_spec *spec)
+        const struct yasl_private_popup_spec *spec)
 {
     if (!popup || popup->closed || !popup->is_popup || !popup->parent ||
         !popup->parent->window || !popup->parent->view ||
@@ -2020,8 +2415,8 @@ static NSImage *image_from_pixels(const uint32_t *pixels, int width, int height)
 }
 
 bool cocoa_display_drag_start(struct cocoa_display *d, struct cocoa_surface *origin,
-                             const struct yasl_drag_image *image,
-                             const struct yasl_drag_listener *l, void *ud)
+                             const struct yasl_private_drag_image *image,
+                             const struct yasl_private_drag_listener *l, void *ud)
 {
     if (!d || !origin || d->drag.active || !l)
         return false;
@@ -2029,7 +2424,7 @@ bool cocoa_display_drag_start(struct cocoa_display *d, struct cocoa_surface *ori
     d->drag.origin = origin;
     d->drag.carried = NULL;
     d->drag.hover = NULL;
-    d->drag.hover_pos = (struct yasl_vector2i){0};
+    d->drag.hover_pos = (struct yasl_private_vector2i){0};
     d->drag.listener = *l;
     d->drag.ud = ud;
     [d->drag.image release];
@@ -2074,7 +2469,7 @@ bool cocoa_display_drag_start(struct cocoa_display *d, struct cocoa_surface *ori
     return true;
 }
 
-bool cocoa_surface_drag_carry(struct cocoa_surface *w, struct yasl_vector2i offset)
+bool cocoa_surface_drag_carry(struct cocoa_surface *w, struct yasl_private_vector2i offset)
 {
     if (!w || w->closed || !darwin_ctx.drag.active)
         return false;
@@ -2088,33 +2483,33 @@ bool cocoa_surface_drag_carry(struct cocoa_surface *w, struct yasl_vector2i offs
     return cocoa_surface_place_under_pointer(w, offset);
 }
 
-bool cocoa_surface_start_interactive_resize(struct cocoa_surface *s, enum yasl_resize_edge edge)
+bool cocoa_surface_start_interactive_resize(struct cocoa_surface *s, enum yasl_private_resize_edge edge)
 {
     (void)s; (void)edge;
     return false;
 }
 
-bool cocoa_surface_show_window_menu(struct cocoa_surface *s, struct yasl_vector2i pos)
+bool cocoa_surface_show_window_menu(struct cocoa_surface *s, struct yasl_private_vector2i pos)
 {
     (void)s; (void)pos;
     return false;
 }
 
 void cocoa_surface_set_callbacks(struct cocoa_surface *w,
-        const struct yasl_window_cbs *cbs, void *ud)
+        const struct yasl_private_window_cbs *cbs, void *ud)
 {
     if (!w || w->closed) return;
-    w->base.callbacks = cbs ? *cbs : (struct yasl_window_cbs){0};
+    w->base.callbacks = cbs ? *cbs : (struct yasl_private_window_cbs){0};
     w->base.ud = ud;
     w->cbs = &w->base.callbacks;
     w->ud = ud;
 }
 
-bool cocoa_surface_poll_event(struct cocoa_surface *w, struct yasl_event *ev)
+bool cocoa_surface_poll_event(struct cocoa_surface *w, struct yasl_private_event *ev)
 {
     if (!w || !ev || !input_queue_pop(&w->input, ev))
         return false;
-    if (ev->type == YASL_EVENT_INPUT_RESET) {
+    if (ev->type == YASL_PRIVATE_EVENT_INPUT_RESET) {
         w->buttons = 0;
         w->tablet_down = false;
         w->mods = 0;
@@ -2126,103 +2521,103 @@ bool cocoa_surface_poll_event(struct cocoa_surface *w, struct yasl_event *ev)
     return true;
 }
 
-struct yasl_timing cocoa_surface_timing(const struct cocoa_surface *w)
+struct yasl_private_timing cocoa_surface_timing(const struct cocoa_surface *w)
 {
-    struct yasl_timing timing = {0};
+    struct yasl_private_timing timing = {0};
     if (w) {
         timing.refresh_ns = w->clock.refresh_ns;
         timing.last_present_ns = w->clock.last_present_ns;
-        timing.next_present_ns = yasl_clock_next_present_ns(&w->clock);
+        timing.next_present_ns = yasl_private_clock_next_present_ns(&w->clock);
         timing.frames_skipped = w->frames_skipped;
         timing.source = w->clock.source;
-        yasl_clock_resize_stats(&w->clock, &timing.resize);
+        yasl_private_clock_resize_stats(&w->clock, &timing.resize);
     }
     return timing;
 }
 
-static struct yasl_display *impl_display_open(struct yasl_loop *loop, const struct yasl_display_spec *spec)
+static struct yasl_private_display *impl_display_open(struct yasl_private_loop *loop, const struct yasl_private_display_spec *spec)
 {
     struct cocoa_display *result = cocoa_display_open(loop, spec);
     return result ? &result->base : NULL;
 }
 
-static void impl_display_close(struct yasl_display *d)
+static void impl_display_close(struct yasl_private_display *d)
 {
     cocoa_display_close((struct cocoa_display *)d);
 }
 
-static uint32_t impl_display_caps(const struct yasl_display *d)
+static uint32_t impl_display_caps(const struct yasl_private_display *d)
 {
     return cocoa_display_caps((const struct cocoa_display *)d);
 }
 
-static int impl_display_dispatch_timeout(struct yasl_display *d, int timeout_ms)
+static int impl_display_dispatch_timeout(struct yasl_private_display *d, int timeout_ms)
 {
     return cocoa_display_dispatch_timeout((struct cocoa_display *)d, timeout_ms);
 }
 
-static void impl_display_flush(struct yasl_display *d)
+static void impl_display_flush(struct yasl_private_display *d)
 {
     cocoa_display_flush((struct cocoa_display *)d);
 }
 
-static int impl_display_double_click_ms(const struct yasl_display *d)
+static int impl_display_double_click_ms(const struct yasl_private_display *d)
 {
     (void)d;
     return (int)lround([NSEvent doubleClickInterval] * 1000.0);
 }
 
-static int impl_display_modifiers(const struct yasl_display *d)
+static int impl_display_modifiers(const struct yasl_private_display *d)
 {
     return cocoa_display_modifiers((const struct cocoa_display *)d);
 }
 
-static void impl_display_copy(struct yasl_display *d, enum yasl_selection sel, const char *text)
+static void impl_display_copy(struct yasl_private_display *d, enum yasl_private_selection sel, const char *text)
 {
     cocoa_display_copy((struct cocoa_display *)d, sel, text);
 }
 
-static void impl_display_paste(struct yasl_display *d, enum yasl_selection sel, struct yasl_surface *target)
+static void impl_display_paste(struct yasl_private_display *d, enum yasl_private_selection sel, struct yasl_surface *target)
 {
     cocoa_display_paste((struct cocoa_display *)d, sel, (struct cocoa_surface *)target);
 }
 
-static bool impl_display_copy_text(struct yasl_display *d, enum yasl_selection sel, const char *text)
+static bool impl_display_copy_text(struct yasl_private_display *d, enum yasl_private_selection sel, const char *text)
 {
     return cocoa_display_copy_text((struct cocoa_display *)d, sel, text);
 }
 
-static bool impl_display_request_paste(struct yasl_display *d, enum yasl_selection sel,
+static bool impl_display_request_paste(struct yasl_private_display *d, enum yasl_private_selection sel,
                                        struct yasl_surface *target, uint64_t request_id)
 {
     return cocoa_display_request_paste((struct cocoa_display *)d, sel,
                                        (struct cocoa_surface *)target, request_id);
 }
 
-static bool impl_display_drag_start(struct yasl_display *d, struct yasl_surface *origin, const struct yasl_drag_image *image, const struct yasl_drag_listener *l, void *ud)
+static bool impl_display_drag_start(struct yasl_private_display *d, struct yasl_surface *origin, const struct yasl_private_drag_image *image, const struct yasl_private_drag_listener *l, void *ud)
 {
     return cocoa_display_drag_start((struct cocoa_display *)d, (struct cocoa_surface *)origin, image, l, ud);
 }
 
-static void impl_display_drag_cancel(struct yasl_display *d)
+static void impl_display_drag_cancel(struct yasl_private_display *d)
 {
-    drag_end((struct cocoa_display *)d, YASL_DRAG_CANCELLED);
+    drag_end((struct cocoa_display *)d, YASL_PRIVATE_DRAG_CANCELLED);
 }
 
-static struct yasl_surface *impl_surface_create_toplevel(struct yasl_display *d,
-        const struct yasl_window_spec *spec, void *graphics_device)
+static struct yasl_surface *impl_surface_create_toplevel(struct yasl_private_display *d,
+        const struct yasl_private_window_spec *spec, void *graphics_device)
 {
     struct cocoa_surface *result = cocoa_surface_create_toplevel((struct cocoa_display *)d, spec, graphics_device);
     return result ? &result->base : NULL;
 }
 
-static struct yasl_surface *impl_surface_create_popup(struct yasl_surface *parent, const struct yasl_popup_spec *spec)
+static struct yasl_surface *impl_surface_create_popup(struct yasl_surface *parent, const struct yasl_private_popup_spec *spec)
 {
     struct cocoa_surface *result = cocoa_surface_create_popup((struct cocoa_surface *)parent, spec);
     return result ? &result->base : NULL;
 }
 
-static bool impl_surface_popup_reposition(struct yasl_surface *popup, const struct yasl_popup_spec *spec)
+static bool impl_surface_popup_reposition(struct yasl_surface *popup, const struct yasl_private_popup_spec *spec)
 {
     return cocoa_surface_popup_reposition((struct cocoa_surface *)popup, spec);
 }
@@ -2238,12 +2633,12 @@ static struct input_queue *impl_surface_input_queue(struct yasl_surface *s)
     return w ? &w->input : NULL;
 }
 
-static struct yasl_display *impl_surface_display(const struct yasl_surface *s)
+static struct yasl_private_display *impl_surface_display(const struct yasl_surface *s)
 {
     return s ? &darwin_ctx.base : NULL;
 }
 
-static void impl_surface_set_callbacks(struct yasl_surface *s, const struct yasl_window_cbs *cbs, void *ud)
+static void impl_surface_set_callbacks(struct yasl_surface *s, const struct yasl_private_window_cbs *cbs, void *ud)
 {
     cocoa_surface_set_callbacks((struct cocoa_surface *)s, cbs, ud);
 }
@@ -2258,17 +2653,17 @@ static void impl_surface_schedule_redraw(struct yasl_surface *s)
     cocoa_surface_schedule_redraw((struct cocoa_surface *)s);
 }
 
-static bool impl_surface_present(struct yasl_surface *s, const struct yasl_framebuffer *fb, const struct yasl_damage_list *damage)
+static bool impl_surface_present(struct yasl_surface *s, const struct yasl_private_framebuffer *fb, const struct yasl_private_damage_list *damage)
 {
     return cocoa_surface_present((struct cocoa_surface *)s, fb, damage);
 }
 
-static struct yasl_geometry impl_surface_geometry(const struct yasl_surface *s)
+static struct yasl_private_geometry impl_surface_geometry(const struct yasl_surface *s)
 {
     return cocoa_surface_geometry((const struct cocoa_surface *)s);
 }
 
-static struct yasl_timing impl_surface_timing(const struct yasl_surface *s)
+static struct yasl_private_timing impl_surface_timing(const struct yasl_surface *s)
 {
     return cocoa_surface_timing((const struct cocoa_surface *)s);
 }
@@ -2276,10 +2671,10 @@ static struct yasl_timing impl_surface_timing(const struct yasl_surface *s)
 static uint64_t impl_surface_frame_time_ns(struct yasl_surface *s, uint64_t now)
 {
     struct cocoa_surface *w = (struct cocoa_surface *)s;
-    return w ? yasl_clock_frame_timestamp_ns(&w->clock, now) : now;
+    return w ? yasl_private_clock_frame_timestamp_ns(&w->clock, now) : now;
 }
 
-static void impl_surface_set_cursor(struct yasl_surface *s, enum yasl_cursor cursor)
+static void impl_surface_set_cursor(struct yasl_surface *s, enum yasl_private_cursor cursor)
 {
     cocoa_surface_set_cursor((struct cocoa_surface *)s, cursor);
 }
@@ -2300,7 +2695,7 @@ static bool impl_surface_ime_preedit_cursor(const struct yasl_surface *s, int *b
     return cocoa_surface_ime_preedit_cursor((const struct cocoa_surface *)s, begin, end);
 }
 
-static void impl_surface_set_ime_caret(struct yasl_surface *s, struct yasl_rect2i caret)
+static void impl_surface_set_ime_caret(struct yasl_surface *s, struct yasl_private_rect2i caret)
 {
     cocoa_surface_set_ime_caret((struct cocoa_surface *)s, caret);
 }
@@ -2310,35 +2705,165 @@ static bool impl_surface_start_interactive_move(struct yasl_surface *s)
     return cocoa_surface_start_interactive_move((struct cocoa_surface *)s);
 }
 
-static bool impl_surface_start_interactive_resize(struct yasl_surface *s, enum yasl_resize_edge edge)
+static bool impl_surface_start_interactive_resize(struct yasl_surface *s, enum yasl_private_resize_edge edge)
 {
     return cocoa_surface_start_interactive_resize((struct cocoa_surface *)s, edge);
 }
 
-static bool impl_surface_show_window_menu(struct yasl_surface *s, struct yasl_vector2i pos)
+static bool impl_surface_show_window_menu(struct yasl_surface *s, struct yasl_private_vector2i pos)
 {
     return cocoa_surface_show_window_menu((struct cocoa_surface *)s, pos);
 }
 
-static bool impl_surface_drag_carry(struct yasl_surface *s, struct yasl_vector2i offset)
+static bool impl_surface_drag_carry(struct yasl_surface *s, struct yasl_private_vector2i offset)
 {
     return cocoa_surface_drag_carry((struct cocoa_surface *)s, offset);
 }
 
-static bool impl_surface_place_under_pointer(struct yasl_surface *s, struct yasl_vector2i at)
+static bool impl_surface_place_under_pointer(struct yasl_surface *s, struct yasl_private_vector2i at)
 {
     return cocoa_surface_place_under_pointer((struct cocoa_surface *)s, at);
 }
 
+static struct yasl_surface *impl_surface_create_gl(struct yasl_private_display *display,
+        const struct yasl_private_window_spec *spec, const int *attrs, struct yasl_surface *share)
+{
+    struct yasl_private_gl_options options;
+    if (!spec || !yasl_private_gl_parse_options(attrs, &options) ||
+        options.api != YASL_PRIVATE_GL_OPENGL || options.debug || (share &&
+        (share->display != display || share->presenter != YASL_PRIVATE_PRESENTER_GL)))
+        return NULL;
+    int profile = options.profile;
+    if (profile == YASL_PRIVATE_GL_ANY)
+        profile = options.major >= 3 ? YASL_PRIVATE_GL_CORE : YASL_PRIVATE_GL_COMPATIBILITY;
+    if (options.forward_compat && profile != YASL_PRIVATE_GL_CORE)
+        return NULL;
+    if ((profile == YASL_PRIVATE_GL_CORE &&
+         (options.major != 3 || options.minor != 2)) ||
+        (profile == YASL_PRIVATE_GL_COMPATIBILITY &&
+         (options.major > 2 || (options.major == 2 && options.minor > 1))))
+        return NULL;
+
+    struct yasl_private_window_spec gl_spec = *spec;
+    gl_spec.external_gpu = true;
+    struct cocoa_surface *w = cocoa_surface_create_toplevel((struct cocoa_display *)display, &gl_spec, NULL);
+    if (!w) return NULL;
+
+    NSOpenGLPixelFormatAttribute pixel_attrs[32];
+    NSUInteger n = 0;
+    pixel_attrs[n++] = NSOpenGLPFAAccelerated;
+    pixel_attrs[n++] = NSOpenGLPFADoubleBuffer;
+    pixel_attrs[n++] = NSOpenGLPFAColorSize;
+    pixel_attrs[n++] = options.red_bits + options.green_bits + options.blue_bits + options.alpha_bits;
+    pixel_attrs[n++] = NSOpenGLPFAAlphaSize;
+    pixel_attrs[n++] = options.alpha_bits;
+    pixel_attrs[n++] = NSOpenGLPFADepthSize;
+    pixel_attrs[n++] = options.depth_bits;
+    pixel_attrs[n++] = NSOpenGLPFAStencilSize;
+    pixel_attrs[n++] = options.stencil_bits;
+    if (options.samples > 0) {
+        pixel_attrs[n++] = NSOpenGLPFASampleBuffers;
+        pixel_attrs[n++] = 1;
+        pixel_attrs[n++] = NSOpenGLPFASamples;
+        pixel_attrs[n++] = options.samples;
+    }
+    if (options.srgb) pixel_attrs[n++] = NSOpenGLPFASRGB;
+    if (profile == YASL_PRIVATE_GL_CORE) {
+        pixel_attrs[n++] = NSOpenGLPFAOpenGLProfile;
+        pixel_attrs[n++] = NSOpenGLProfileVersion3_2Core;
+    } else if (profile == YASL_PRIVATE_GL_COMPATIBILITY) {
+        pixel_attrs[n++] = NSOpenGLPFAOpenGLProfile;
+        pixel_attrs[n++] = NSOpenGLProfileVersionLegacy;
+    }
+    pixel_attrs[n++] = 0;
+
+    NSOpenGLPixelFormat *format = [[NSOpenGLPixelFormat alloc] initWithAttributes:pixel_attrs];
+    NSOpenGLContext *shared = share ? ((struct cocoa_surface *)share)->gl_context : nil;
+    if (format)
+        w->gl_context = [[NSOpenGLContext alloc] initWithFormat:format shareContext:shared];
+    [format release];
+    if (!w->gl_context) {
+        cocoa_surface_destroy(w);
+        reap_dead((struct cocoa_display *)display);
+        return NULL;
+    }
+    [w->view setLayer:[CALayer layer]];
+    w->layer = nil;
+    [w->gl_context setView:w->view];
+    w->base.presenter = YASL_PRIVATE_PRESENTER_GL;
+    return &w->base;
+}
+
+static bool impl_gl_make_current(struct yasl_private_display *display, struct yasl_surface *surface)
+{
+    (void)display;
+    if (!surface) {
+        [NSOpenGLContext clearCurrentContext];
+        return true;
+    }
+    struct cocoa_surface *w = (struct cocoa_surface *)surface;
+    if (w->base.presenter != YASL_PRIVATE_PRESENTER_GL || !w->gl_context || w->closed)
+        return false;
+    [w->gl_context makeCurrentContext];
+    return [NSOpenGLContext currentContext] == w->gl_context;
+}
+
+static yasl_private_gl_proc impl_gl_get_proc_address(struct yasl_private_display *display, const char *name)
+{
+    (void)display;
+    return name ? (yasl_private_gl_proc)dlsym(RTLD_DEFAULT, name) : NULL;
+}
+
+static bool impl_gl_swap_interval(struct yasl_private_display *display, struct yasl_surface *surface, int interval)
+{
+    (void)display;
+    struct cocoa_surface *w = (struct cocoa_surface *)surface;
+    if (!w || w->base.presenter != YASL_PRIVATE_PRESENTER_GL || !w->gl_context || w->closed)
+        return false;
+    [w->gl_context setValues:&interval forParameter:NSOpenGLCPSwapInterval];
+    return true;
+}
+
+static bool impl_gl_swap_buffers(struct yasl_private_display *display, struct yasl_surface *surface)
+{
+    (void)display;
+    struct cocoa_surface *w = (struct cocoa_surface *)surface;
+    if (!w || w->base.presenter != YASL_PRIVATE_PRESENTER_GL || !w->gl_context || w->closed)
+        return false;
+    [w->gl_context flushBuffer];
+    yasl_private_clock_presented(&w->clock, yasl_private_loop_now_ns(), false);
+    return true;
+}
+
+static void *impl_surface_get_metal_layer(struct yasl_surface *surface)
+{
+    struct cocoa_surface *w = (struct cocoa_surface *)surface;
+    return w && (w->base.presenter == YASL_PRIVATE_PRESENTER_NONE ||
+                 w->base.presenter == YASL_PRIVATE_PRESENTER_METAL) ? (void *)w->layer : NULL;
+}
+
+static bool impl_surface_update_text_input(struct yasl_surface *surface)
+{
+    struct cocoa_surface *w = (struct cocoa_surface *)surface;
+    if (!w || w->closed || w->destroyed || !w->view) return false;
+    if (w->base.text_input_active) {
+        [w->window makeFirstResponder:w->view];
+    } else {
+        [w->view.inputContext discardMarkedText];
+        if (w->preedit) [w->view unmarkText];
+    }
+    return true;
+}
+
 static bool impl_surface_read_pixels(struct yasl_surface *s, uint32_t *out, size_t cap,
-                                     struct yasl_vector2i *size)
+                                     struct yasl_private_vector2i *size)
 {
     struct cocoa_surface *w = (struct cocoa_surface *)s;
     /* did_present stays set from the last draw until the next one starts, and
      * pixels are reallocated only when a draw starts. */
     if (w->closed || w->rendering || !w->did_present || !w->software_queue || !w->pixels)
         return false;
-    return yasl_copy_frame(w->pixels, w->shown_size, out, cap, size);
+    return yasl_private_copy_frame(w->pixels, w->shown_size, out, cap, size);
 }
 
 static bool impl_surface_bell(struct yasl_surface *s)
@@ -2349,7 +2874,7 @@ static bool impl_surface_bell(struct yasl_surface *s)
     return true;
 }
 
-static void *impl_display_get_native_handle(struct yasl_display *d)
+static void *impl_display_get_native_handle(struct yasl_private_display *d)
 {
     return d ? (void *)NSApp : NULL;
 }
@@ -2361,19 +2886,26 @@ static void *impl_surface_get_native_handle(struct yasl_surface *s)
 }
 
 static bool impl_surface_get_native_frame(struct yasl_surface *s,
-        const struct yasl_framebuffer *target, struct yasl_native_frame *out)
+        const struct yasl_private_framebuffer *target, struct yasl_private_native_frame *out)
 {
     struct cocoa_surface *w = (struct cocoa_surface *)s;
     if (w->closed || !w->rendering || w->did_present || !w->drawable ||
         target->pixels != w->frame.target.pixels ||
         target->size.x != w->size.x || target->size.y != w->size.y)
         return false;
-    *out = (struct yasl_native_frame){(void *)w->drawable, w->transaction};
+    *out = (struct yasl_private_native_frame){(void *)w->drawable, w->transaction};
     return true;
 }
 
-const struct yasl_backend_ops yasl_cocoa_backend = {
-    .type = YASL_BACKEND_COCOA,
+const struct yasl_private_backend_ops yasl_private_cocoa_backend = {
+    .type = YASL_PRIVATE_BACKEND_COCOA,
+    .surface_create_gl = impl_surface_create_gl,
+    .gl_make_current = impl_gl_make_current,
+    .gl_get_proc_address = impl_gl_get_proc_address,
+    .gl_swap_interval = impl_gl_swap_interval,
+    .gl_swap_buffers = impl_gl_swap_buffers,
+    .surface_get_metal_layer = impl_surface_get_metal_layer,
+    .surface_update_text_input = impl_surface_update_text_input,
     .display_open = impl_display_open,
     .display_close = impl_display_close,
     .display_caps = impl_display_caps,
@@ -2421,20 +2953,20 @@ const struct yasl_backend_ops yasl_cocoa_backend = {
     .surface_get_native_frame = impl_surface_get_native_frame,
 };
 
-NSApplication *yasl_cocoa_display_get_application(struct yasl_display *d)
+NSApplication *yasl_private_cocoa_display_get_application(struct yasl_private_display *d)
 {
-    return (d && yasl_display_backend(d) == YASL_BACKEND_COCOA) ?
-        (NSApplication *)yasl_display_get_native_handle(d) : nil;
+    return (d && yasl_private_display_backend(d) == YASL_PRIVATE_BACKEND_COCOA) ?
+        (NSApplication *)yasl_private_display_get_native_handle(d) : nil;
 }
 
-NSWindow *yasl_cocoa_surface_get_window(struct yasl_surface *s)
+NSWindow *yasl_private_cocoa_surface_get_window(struct yasl_surface *s)
 {
-    return (s && s->display && yasl_display_backend(s->display) == YASL_BACKEND_COCOA) ?
-        (NSWindow *)yasl_surface_get_native_handle(s) : nil;
+    return (s && s->display && yasl_private_display_backend(s->display) == YASL_PRIVATE_BACKEND_COCOA) ?
+        (NSWindow *)yasl_private_surface_get_native_handle(s) : nil;
 }
 
-NSView *yasl_cocoa_surface_get_view(struct yasl_surface *s)
+NSView *yasl_private_cocoa_surface_get_view(struct yasl_surface *s)
 {
-    NSWindow *w = yasl_cocoa_surface_get_window(s);
+    NSWindow *w = yasl_private_cocoa_surface_get_window(s);
     return w ? w.contentView : nil;
 }