Fix zombie window issue if macOS startup activation is slow.

examples/slow_window_start.nim

@@ -0,0 +1,87 @@
+import
+  std/[os, strformat],
+  windy, vmath, boxy, opengl
+
+const
+  SlowStartMs = 3500
+
+var
+  window: Window
+  bxy: Boxy
+  squareSize = 28.0
+  clicked = false
+  moveCount = 0
+
+proc drawFrame() =
+  ## Draws the cursor-following square and crosshair.
+  bxy.beginFrame(window.size)
+  bxy.saveTransform()
+
+  let
+    scale = window.contentScale
+    logicalSize = window.size.vec2 / scale
+    cursorPos = window.mousePos.vec2 / scale
+    halfSize = squareSize / 2.0
+    squareColor =
+      if clicked:
+        color(0.2, 0.7, 1.0, 0.9)
+      else:
+        color(1.0, 0.3, 0.3, 0.8)
+
+  bxy.scale(scale)
+  bxy.drawRect(
+    rect(0, 0, logicalSize.x, logicalSize.y),
+    color(0.1, 0.1, 0.1, 1.0)
+  )
+  bxy.drawRect(
+    rect(
+      cursorPos.x - halfSize,
+      cursorPos.y - halfSize,
+      squareSize,
+      squareSize
+    ),
+    squareColor
+  )
+  bxy.drawRect(
+    rect(cursorPos.x - 1, 0, 2, logicalSize.y),
+    color(0.3, 1.0, 0.3, 0.5)
+  )
+  bxy.drawRect(
+    rect(0, cursorPos.y - 1, logicalSize.x, 2),
+    color(0.3, 1.0, 0.3, 0.5)
+  )
+
+  bxy.restoreTransform()
+  bxy.endFrame()
+  window.swapBuffers()
+
+window = newWindow("Slow Window Start", ivec2(1280, 800))
+window.makeContextCurrent()
+loadExtensions()
+bxy = newBoxy()
+
+window.onMouseMove = proc() =
+  moveCount += 1
+
+window.onButtonPress = proc(button: Button) =
+  case button:
+  of MouseLeft:
+    clicked = not clicked
+    echo &"Left click toggled color. Mouse moves seen: {moveCount}"
+  else:
+    discard
+
+window.onFrame = proc() =
+  drawFrame()
+
+echo "Slow window start repro."
+echo "The window is visible before the event loop is allowed to run."
+echo "After the delay, move the mouse and click the square."
+
+drawFrame()
+echo "Delaying for 3,500 ms."
+sleep(SlowStartMs)
+echo "Delay done."
+
+while not window.closeRequested:
+  pollEvents()

src/windy/platforms/macos/macdefs.nim

@@ -49,6 +49,7 @@ type
   NSNotification* = distinct NSObject
   NSEvent* = distinct NSObject
   NSDate* = distinct NSObject
+  NSRunLoop* = distinct NSObject
   NSRunLoopMode* = distinct NSString
   NSMenu* = distinct NSObject
   NSMenuItem* = distinct NSObject
@@ -190,6 +191,16 @@ objc:
   ): NSEvent
   proc sendEvent*(self: NSApplication, x: NSEvent)
   proc distantPast*(class: typedesc[NSDate]): NSDate
+  proc dateWithTimeIntervalSinceNow*(
+    class: typedesc[NSDate],
+    x: float64
+  ): NSDate
+  proc currentRunLoop*(class: typedesc[NSRunLoop]): NSRunLoop
+  proc runMode*(
+    self: NSRunLoop,
+    x: NSRunLoopMode,
+    beforeDate: NSDate
+  ): bool
   proc addItem*(self: NSMenu, x: NSMenuItem)
   proc initWithTitle*(
     self: NSMenuItem,

src/windy/platforms/macos/platform.nim

@@ -37,8 +37,11 @@ type
     # AppKit applies this state asynchronously via delegate callbacks.
     fullscreenState: bool
     minimizedState: bool
+    activationSettlePolls: int
 
 const
+  ActivationSettlePolls = 60
+  ActivationSettleSeconds = 0.001
   decoratedResizableWindowMask =
     NSWindowStyleMaskTitled or NSWindowStyleMaskClosable or
     NSWindowStyleMaskMiniaturizable or NSWindowStyleMaskResizable
@@ -160,12 +163,25 @@ proc `title=`*(window: Window, title: string) =
 proc `icon=`*(window: Window, icon: Image) =
   window.state.icon = icon
 
+proc requestActivation(window: Window) =
+  ## Shows the window and asks AppKit to activate this app.
+  window.inner.makeKeyAndOrderFront(0.ID)
+  NSApp.activateIgnoringOtherApps(true)
+
+proc settleRunLoop() =
+  ## Gives AppKit a short turn to deliver activation notifications.
+  discard NSRunLoop.currentRunLoop.runMode(
+    NSDefaultRunLoopMode,
+    NSDate.dateWithTimeIntervalSinceNow(ActivationSettleSeconds)
+  )
+
 proc `visible=`*(window: Window, visible: bool) =
   autoreleasepool:
     if visible:
-      window.inner.makeKeyAndOrderFront(0.ID)
-      NSApp.activateIgnoringOtherApps(true)
+      window.activationSettlePolls = ActivationSettlePolls
+      window.requestActivation()
     else:
+      window.activationSettlePolls = 0
       window.inner.orderOut(0.ID)
 
 proc `style=`*(window: Window, windowStyle: WindowStyle) =
@@ -320,7 +336,6 @@ proc applicationDidFinishLaunching(
   notification: NSNotification
 ): ID {.cdecl.} =
   NSApp.setPresentationOptions(NSApplicationPresentationDefault)
-  NSApp.activateIgnoringOtherApps(true)
 
 proc windowDidResize(
   self: ID,
@@ -888,7 +903,22 @@ proc processFlagsChanged(event: NSEvent) =
   else:
     window.handleButtonPress(button)
 
+proc settleActivationRequests() =
+  ## Replays activation while AppKit catches up after delayed startup.
+  var pending = false
+  for window in windows:
+    if window.activationSettlePolls == 0:
+      continue
+    dec window.activationSettlePolls
+    pending = true
+    window.requestActivation()
+  if pending:
+    settleRunLoop()
+
 proc pollEvents*() =
+  autoreleasepool:
+    settleActivationRequests()
+
   # Draw first (in case a message closes a window or similar)
   for window in windows:
     if window.onFrame != nil:
@@ -1077,8 +1107,6 @@ proc newWindow*(
     result.fullscreenState =
       (result.inner.styleMask and NSWindowStyleMaskFullScreen) != 0
 
-  pollEvents() # This can cause lots of issues, potential workaround needed
-
 proc title*(window: Window): string =
   window.state.title
 

tests/run_all.nim

@@ -21,6 +21,7 @@ const Examples = [
   "property_changes",
   "screens",
   "scrollwheel",
+  "slow_window_start",
   "system_cursors",
   "tray",
   "websocket",