From a705f546bba1f3fb973aae2cdeb9ed8d08cf4f16 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Tue, 7 Feb 2023 11:46:18 +0100
Subject: [PATCH] Enable resizing during fullscreen transition.

macOS seems to tie resizing of the NSView inside the window to the resizable style mask of the window somehow. If we programmatically transition a non-resizable window to fullscreen, the inner NSView's size isn't changed, so we need to make the window resizable during the fullscreen transition.

Makes the final two failing `WindowState` integration tests pass.
---
 native/Avalonia.Native/src/OSX/WindowImpl.mm | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/native/Avalonia.Native/src/OSX/WindowImpl.mm b/native/Avalonia.Native/src/OSX/WindowImpl.mm
index e4bbe24cb8..47e83f8d56 100644
--- a/native/Avalonia.Native/src/OSX/WindowImpl.mm
+++ b/native/Avalonia.Native/src/OSX/WindowImpl.mm
@@ -146,11 +146,13 @@ bool WindowImpl::CanBecomeKeyWindow()
 
 void WindowImpl::StartStateTransition() {
     _transitioningWindowState = true;
+    UpdateStyle();
 }
 
 void WindowImpl::EndStateTransition() {
     _transitioningWindowState = false;
-    
+    UpdateStyle();
+
     // Ensure correct order of child windows after fullscreen transition.
     BringToFront();
 }
@@ -573,7 +575,7 @@ NSWindowStyleMask WindowImpl::CalculateStyleMask() {
         case SystemDecorationsFull:
             s = s | NSWindowStyleMaskTitled | NSWindowStyleMaskClosable;
 
-            if (_canResize && _isEnabled) {
+            if ((_canResize && _isEnabled) || _transitioningWindowState) {
                 s = s | NSWindowStyleMaskResizable;
             }
             break;