Merge branch 'master' into 9705-protected-owning-grid

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -1409,7 +1409,7 @@ namespace Avalonia.Win32.Interop
         [DllImport("user32.dll")]
         public static extern bool TranslateMessage(ref MSG lpMsg);
 
-        [DllImport("user32.dll")]
+        [DllImport("user32.dll", CharSet = CharSet.Unicode)]
         public static extern bool UnregisterClass(string lpClassName, IntPtr hInstance);
 
         [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode, EntryPoint = "SetWindowTextW")]

src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs

@@ -10,6 +10,7 @@ using Avalonia.Controls.Remote;
 using Avalonia.Input;
 using Avalonia.Input.Raw;
 using Avalonia.Platform;
+using Avalonia.Threading;
 using Avalonia.Win32.Automation;
 using Avalonia.Win32.Input;
 using Avalonia.Win32.Interop.Automation;
@@ -106,6 +107,9 @@ namespace Avalonia.Win32
                         _touchDevice?.Dispose();
                         //Free other resources
                         Dispose();
+
+                        // Schedule cleanup of anything that requires window to be destroyed
+                        Dispatcher.UIThread.Post(AfterCloseCleanup);
                         return IntPtr.Zero;
                     }
 

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -643,12 +643,6 @@ namespace Avalonia.Win32
                 _hwnd = IntPtr.Zero;
             }
 
-            if (_className != null)
-            {
-                UnregisterClass(_className, GetModuleHandle(null));
-                _className = null;
-            }
-
             _framebuffer.Dispose();
         }
 
@@ -1144,6 +1138,15 @@ namespace Avalonia.Win32
             }
         }
 
+        private void AfterCloseCleanup()
+        {
+            if (_className != null)
+            {
+                UnregisterClass(_className, GetModuleHandle(null));
+                _className = null;
+            }
+        }
+
         private void MaximizeWithoutCoveringTaskbar()
         {
             IntPtr monitor = MonitorFromWindow(_hwnd, MONITOR.MONITOR_DEFAULTTONEAREST);