diff --git a/MatterControl.Winforms/WinformsSingleWindowProvider.cs b/MatterControl.Winforms/WinformsSingleWindowProvider.cs
index 4d64481a6..7830e3467 100644
--- a/MatterControl.Winforms/WinformsSingleWindowProvider.cs
+++ b/MatterControl.Winforms/WinformsSingleWindowProvider.cs
@@ -46,8 +46,9 @@ namespace MatterHackers.MatterControl
 				platformWindow = openGLPlatformWindow;
 			}
 
-			systemWindow.PlatformWindow = openGLPlatformWindow;
 			base.ShowSystemWindow(systemWindow);
+
+			systemWindow.PlatformWindow = openGLPlatformWindow;
 		}
 	}
 }
\ No newline at end of file
diff --git a/MatterControlLib/CustomWidgets/SingleWindowProvider.cs b/MatterControlLib/CustomWidgets/SingleWindowProvider.cs
index 6aa895c78..6cb3f2e2f 100644
--- a/MatterControlLib/CustomWidgets/SingleWindowProvider.cs
+++ b/MatterControlLib/CustomWidgets/SingleWindowProvider.cs
@@ -56,6 +56,11 @@ namespace MatterHackers.Agg.UI
 			}
 			else
 			{
+				if (systemWindow.PlatformWindow != null)
+				{
+					return;
+				}
+
 				var overlayWindow = new SystemWindow(_openWindows.FirstOrDefault().Width, _openWindows.FirstOrDefault().Height)
 				{
 					PlatformWindow = platformWindow