fix(macos): dispatch NSWindow UI ops to main thread

Flutter calls Window::Show(), Focus(), etc. from the io.flutter.ui
thread, not the main thread. macOS requires NSWindow ordering/visibility
operations on the main thread — calling makeKeyAndOrderFront: from
another thread triggers EXC_BREAKPOINT with 'Must only be used from
the main thread'.

All void methods that touch window ordering, visibility, key state,
frame, or dragging now dispatch async to the main queue via
RunOnMainThread(). Getters stay synchronous (they read state and
don't crash off-main-thread).

Author: brennodewinter

packages/cnativeapi/cxx_impl/src/platform/macos/window_macos.mm

@@ -12,6 +12,19 @@
 // Key for associated objects (used by both window_macos.mm and window_manager_macos.mm)
 const void* kWindowIdKey = &kWindowIdKey;
 
+// NSWindow UI operations (ordering, visibility, key state) must run on the main
+// thread. Flutter calls these from the UI thread (io.flutter.ui), not the main
+// thread, so we dispatch async. The old window_manager package did the same.
+// ponytail: async means Show() returns before the window is actually visible;
+// acceptable — callers don't depend on synchronous visibility.
+static inline void RunOnMainThread(dispatch_block_t block) {
+  if ([NSThread isMainThread]) {
+    block();
+  } else {
+    dispatch_async(dispatch_get_main_queue(), block);
+  }
+}
+
 namespace nativeapi {
 
 // Private implementation class
@@ -67,82 +80,85 @@
 Window::~Window() {}
 
 void Window::Focus() {
-  [pimpl_->ns_window_ makeKeyAndOrderFront:nil];
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{ [w makeKeyAndOrderFront:nil]; });
 }
 
 void Window::Blur() {
-  [pimpl_->ns_window_ orderBack:nil];
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{ [w orderBack:nil]; });
 }
 
 bool Window::IsFocused() const {
   return [pimpl_->ns_window_ isKeyWindow];
 }
 
 void Window::Show() {
-  [pimpl_->ns_window_ setIsVisible:YES];
-  // Panels receive key focus when shown but should not activate the app.
-  if (![pimpl_->ns_window_ isKindOfClass:[NSPanel class]]) {
-    [[NSApplication sharedApplication] activateIgnoringOtherApps:YES];
-  }
-  [pimpl_->ns_window_ makeKeyAndOrderFront:nil];
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{
+    [w setIsVisible:YES];
+    // Panels receive key focus when shown but should not activate the app.
+    if (![w isKindOfClass:[NSPanel class]]) {
+      [[NSApplication sharedApplication] activateIgnoringOtherApps:YES];
+    }
+    [w makeKeyAndOrderFront:nil];
+  });
 }
 
 void Window::ShowInactive() {
-  [pimpl_->ns_window_ setIsVisible:YES];
-  [pimpl_->ns_window_ orderFrontRegardless];
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{
+    [w setIsVisible:YES];
+    [w orderFrontRegardless];
+  });
 }
 
 void Window::Hide() {
-  [pimpl_->ns_window_ setIsVisible:NO];
-  [pimpl_->ns_window_ orderOut:nil];
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{
+    [w setIsVisible:NO];
+    [w orderOut:nil];
+  });
 }
 
 bool Window::IsVisible() const {
   return [pimpl_->ns_window_ isVisible];
 }
 
 void Window::Maximize() {
-  if (!IsMaximized()) {
-    [pimpl_->ns_window_ zoom:nil];
-  }
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{ if (![w isZoomed]) [w zoom:nil]; });
 }
 
 void Window::Unmaximize() {
-  if (IsMaximized()) {
-    [pimpl_->ns_window_ zoom:nil];
-  }
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{ if ([w isZoomed]) [w zoom:nil]; });
 }
 
 bool Window::IsMaximized() const {
   return [pimpl_->ns_window_ isZoomed];
 }
 
 void Window::Minimize() {
-  if (!IsMinimized()) {
-    [pimpl_->ns_window_ miniaturize:nil];
-  }
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{ if (![w isMiniaturized]) [w miniaturize:nil]; });
 }
 
 void Window::Restore() {
-  if (IsMinimized()) {
-    [pimpl_->ns_window_ deminiaturize:nil];
-  }
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{ if ([w isMiniaturized]) [w deminiaturize:nil]; });
 }
 
 bool Window::IsMinimized() const {
   return [pimpl_->ns_window_ isMiniaturized];
 }
 
 void Window::SetFullScreen(bool is_full_screen) {
-  if (is_full_screen) {
-    if (!IsFullScreen()) {
-      [pimpl_->ns_window_ toggleFullScreen:nil];
-    }
-  } else {
-    if (IsFullScreen()) {
-      [pimpl_->ns_window_ toggleFullScreen:nil];
-    }
-  }
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{
+    bool fs = ([w styleMask] & NSWindowStyleMaskFullScreen) != 0;
+    if (is_full_screen != fs) [w toggleFullScreen:nil];
+  });
 }
 
 bool Window::IsFullScreen() const {
@@ -153,10 +169,10 @@
 //// Color Window::GetBackgroundColor() const;
 
 void Window::SetBounds(Rectangle bounds) {
-  // Convert from topLeft coordinate system to bottom-left (macOS default)
+  NSWindow* w = pimpl_->ns_window_;
   NSRect topLeftRect = NSMakeRect(bounds.x, bounds.y, bounds.width, bounds.height);
   NSRect nsRect = NSRectExt::bottomLeft(topLeftRect);
-  [pimpl_->ns_window_ setFrame:nsRect display:YES];
+  RunOnMainThread(^{ [w setFrame:nsRect display:YES]; });
 }
 
 Rectangle Window::GetBounds() const {
@@ -169,15 +185,18 @@
 }
 
 void Window::SetSize(Size size, bool animate) {
-  NSRect frame = [pimpl_->ns_window_ frame];
-  frame.origin.y += (frame.size.height - size.height);
-  frame.size.width = size.width;
-  frame.size.height = size.height;
-  if (animate) {
-    [[pimpl_->ns_window_ animator] setFrame:frame display:YES animate:YES];
-  } else {
-    [pimpl_->ns_window_ setFrame:frame display:YES];
-  }
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{
+    NSRect frame = [w frame];
+    frame.origin.y += (frame.size.height - size.height);
+    frame.size.width = size.width;
+    frame.size.height = size.height;
+    if (animate) {
+      [[w animator] setFrame:frame display:YES animate:YES];
+    } else {
+      [w setFrame:frame display:YES];
+    }
+  });
 }
 
 Size Window::GetSize() const {
@@ -338,12 +357,13 @@
 }
 
 void Window::SetPosition(Point point) {
-  // Convert from topLeft coordinate system to bottom-left (macOS default)
-  // We need the window height to correctly convert the top-left position
-  NSRect frame = [pimpl_->ns_window_ frame];
-  CGPoint topLeftPoint = {point.x, point.y};
-  NSPoint bottomLeft = NSPointExt::bottomLeftForWindow(topLeftPoint, frame.size.height);
-  [pimpl_->ns_window_ setFrameOrigin:bottomLeft];
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{
+    NSRect frame = [w frame];
+    CGPoint topLeftPoint = {point.x, point.y};
+    NSPoint bottomLeft = NSPointExt::bottomLeftForWindow(topLeftPoint, frame.size.height);
+    [w setFrameOrigin:bottomLeft];
+  });
 }
 
 Point Window::GetPosition() const {
@@ -355,8 +375,8 @@
 }
 
 void Window::Center() {
-  // Use NSWindow's center method which automatically centers on the main screen
-  [pimpl_->ns_window_ center];
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{ [w center]; });
 }
 
 void Window::SetTitle(std::string title) {
@@ -525,10 +545,12 @@
 }
 
 void Window::StartDragging() {
-  NSWindow* window = pimpl_->ns_window_;
-  if (window.currentEvent) {
-    [window performWindowDragWithEvent:window.currentEvent];
-  }
+  NSWindow* w = pimpl_->ns_window_;
+  RunOnMainThread(^{
+    if (w.currentEvent) {
+      [w performWindowDragWithEvent:w.currentEvent];
+    }
+  });
 }
 
 void Window::StartResizing() {}