From 24dd2b4459980dd379652485d9b005dec4f39483 Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Fri, 1 May 2020 18:04:26 -0300
Subject: [PATCH] [OSX] borderless window can transistion from FullScreen to
 Maximised correctly.

---
 native/Avalonia.Native/src/OSX/window.h  |  2 ++
 native/Avalonia.Native/src/OSX/window.mm | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/native/Avalonia.Native/src/OSX/window.h b/native/Avalonia.Native/src/OSX/window.h
index 14fa054cbf..ec8fe9e6ee 100644
--- a/native/Avalonia.Native/src/OSX/window.h
+++ b/native/Avalonia.Native/src/OSX/window.h
@@ -37,6 +37,8 @@ struct IWindowStateChanged
     virtual void WindowStateChanged () = 0;
     virtual void StartStateTransition () = 0;
     virtual void EndStateTransition () = 0;
+    virtual SystemDecorations Decorations () = 0;
+    virtual AvnWindowState WindowState () = 0;
 };
 
 #endif /* window_h */
diff --git a/native/Avalonia.Native/src/OSX/window.mm b/native/Avalonia.Native/src/OSX/window.mm
index 50e04d9def..f8dc07063e 100644
--- a/native/Avalonia.Native/src/OSX/window.mm
+++ b/native/Avalonia.Native/src/OSX/window.mm
@@ -499,6 +499,16 @@ private:
         _transitioningWindowState = false;
     }
     
+    SystemDecorations Decorations () override
+    {
+        return _decorations;
+    }
+    
+    AvnWindowState WindowState () override
+    {
+        return _lastWindowState;
+    }
+    
     void WindowStateChanged () override
     {
         if(!_inSetWindowState && !_transitioningWindowState)
@@ -1587,6 +1597,13 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     if(parent != nullptr)
     {
         parent->EndStateTransition();
+        
+        if(parent->Decorations() != SystemDecorationsFull && parent->WindowState() == Maximized)
+        {
+            NSRect screenRect = [[self screen] visibleFrame];
+            [self setFrame:screenRect display:YES];
+        }
+        
         parent->WindowStateChanged();
     }
 }