From 3a1486be5622a53c8340cd8bcef8a34d34afd9ed Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Wed, 20 May 2020 17:06:00 -0300
Subject: [PATCH] check composition is allowed before allowing extended
 windows.

---
 src/Windows/Avalonia.Win32/WindowImpl.cs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/Windows/Avalonia.Win32/WindowImpl.cs b/src/Windows/Avalonia.Win32/WindowImpl.cs
index af1e8e06ce..7474bdd10a 100644
--- a/src/Windows/Avalonia.Win32/WindowImpl.cs
+++ b/src/Windows/Avalonia.Win32/WindowImpl.cs
@@ -670,6 +670,11 @@ namespace Avalonia.Win32
         {
             if (!_isClientAreaExtended)
             {
+                if(DwmIsCompositionEnabled(out bool compositionEnabled) < 0 || !compositionEnabled)
+                {
+                    return;
+                }
+
                 RECT border_thickness = new RECT();
                 MARGINS margins = new MARGINS();