From 2364f664179444e954934c2fd3d41f551e5d51e2 Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Wed, 19 May 2021 11:19:56 +0100
Subject: [PATCH] Merge pull request #5943 from
 AvaloniaUI/fixes/missing-osx-shadow-border

trick to make OSX invalidate the shadow.
---
 native/Avalonia.Native/src/OSX/window.h  |  1 +
 native/Avalonia.Native/src/OSX/window.mm | 19 ++++++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/native/Avalonia.Native/src/OSX/window.h b/native/Avalonia.Native/src/OSX/window.h
index b1f64bca88..6a4ca2b8d8 100644
--- a/native/Avalonia.Native/src/OSX/window.h
+++ b/native/Avalonia.Native/src/OSX/window.h
@@ -34,6 +34,7 @@ class WindowBaseImpl;
 -(double) getScaling;
 -(double) getExtendedTitleBarHeight;
 -(void) setIsExtended:(bool)value;
+-(void) updateShadow;
 @end
 
 struct INSWindowHolder
diff --git a/native/Avalonia.Native/src/OSX/window.mm b/native/Avalonia.Native/src/OSX/window.mm
index d7afbdaa3a..e7c144b2d3 100644
--- a/native/Avalonia.Native/src/OSX/window.mm
+++ b/native/Avalonia.Native/src/OSX/window.mm
@@ -124,7 +124,11 @@ public:
             [Window setTitle:_lastTitle];
             
             _shown = true;
-        
+            
+            dispatch_async(dispatch_get_main_queue(), ^{
+                [Window updateShadow];
+            });
+            
             return S_OK;
         }
     }
@@ -1838,6 +1842,19 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     double _lastScaling;
 }
 
+- (void)updateShadow
+{
+    // Common problem in Cocoa where [invalidateShadow] does work,
+    // This hack forces Cocoa to invalidate the shadow.
+    
+    NSRect frame = [self frame];
+    NSRect updatedFrame = NSMakeRect(frame.origin.x, frame.origin.y, frame.size.width + 1.0, frame.size.height + 1.0);
+    [self setFrame:updatedFrame display:YES];
+    [self setFrame:frame display:YES];
+    
+    [self invalidateShadow];
+}
+
 -(void) setIsExtended:(bool)value;
 {
     _isExtended = value;