[gtk/wip/chergert/macos-fixes] macos: fix unmaximize opacity around edges of window

[Christian Hergert <chergert src gnome org>]

commit f2efb0f28d194d006d157366d781b6477a0af022
Author: Christian Hergert <christian hergert me>
Date:   Thu Feb 3 19:21:59 2022 -0800

    macos: fix unmaximize opacity around edges of window

 gdk/macos/GdkMacosWindow.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/gdk/macos/GdkMacosWindow.c b/gdk/macos/GdkMacosWindow.c
index 750c21d966..8dda79ab4d 100644
--- a/gdk/macos/GdkMacosWindow.c
+++ b/gdk/macos/GdkMacosWindow.c
@@ -214,7 +214,14 @@ typedef NSString *CALayerContentsGravity;
    * as we are leaving maximized state.
    */
   if ((style_mask & NSWindowStyleMaskTitled) == 0 && [self isOpaque])
-    [self setOpaque:NO];
+    {
+      GdkSurface *surface = GDK_SURFACE ([self gdkSurface]);
+
+      [self setOpaque:NO];
+
+      /* Force updating of various styling, regions, etc */
+      _gdk_surface_update_size (surface);
+    }
 }
 
 -(void)windowDidMove:(NSNotification *)aNotification