diff --git a/native/Avalonia.Native/src/OSX/window.mm b/native/Avalonia.Native/src/OSX/window.mm
index 14fe60ab0b..7a6e7dc72f 100644
--- a/native/Avalonia.Native/src/OSX/window.mm
+++ b/native/Avalonia.Native/src/OSX/window.mm
@@ -641,6 +641,7 @@ private:
         [Window setCanBecomeKeyAndMain];
         [Window disableCursorRects];
         [Window setTabbingMode:NSWindowTabbingModeDisallowed];
+        [Window setCollectionBehavior:NSWindowCollectionBehaviorFullScreenPrimary];
     }
     
     void HideOrShowTrafficLights ()
@@ -1091,14 +1092,7 @@ private:
     {
         _fullScreenActive = true;
         
-        [Window setHasShadow:YES];
-        [Window setTitleVisibility:NSWindowTitleVisible];
-        [Window setTitlebarAppearsTransparent:NO];
         [Window setTitle:_lastTitle];
-        
-        Window.styleMask = Window.styleMask | NSWindowStyleMaskTitled | NSWindowStyleMaskResizable;
-        Window.styleMask = Window.styleMask & ~NSWindowStyleMaskFullSizeContentView;
-    
         [Window toggleFullScreen:nullptr];
     }
     
@@ -1672,6 +1666,7 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
 
     switch(event.buttonNumber)
     {
+        case 2:
         case 3:
             _isMiddlePressed = true;
             [self mouseEvent:event withType:MiddleButtonDown];
@@ -1704,6 +1699,7 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
 {
     switch(event.buttonNumber)
     {
+        case 2:
         case 3:
             _isMiddlePressed = false;
             [self mouseEvent:event withType:MiddleButtonUp];
diff --git a/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs b/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs
index 1a78792173..326d1a3f53 100644
--- a/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs
+++ b/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs
@@ -39,7 +39,7 @@ namespace Avalonia.Threading
             if (Dispatcher.UIThread.CheckAccess())
                 d(state);
             else
-                Dispatcher.UIThread.InvokeAsync(() => d(state), DispatcherPriority.Send).Wait();
+                Dispatcher.UIThread.InvokeAsync(() => d(state), DispatcherPriority.Send).GetAwaiter().GetResult();
         }
 
 
diff --git a/src/Avalonia.Controls/AutoCompleteBox.cs b/src/Avalonia.Controls/AutoCompleteBox.cs
index 5a6e78f441..0e946126ea 100644
--- a/src/Avalonia.Controls/AutoCompleteBox.cs
+++ b/src/Avalonia.Controls/AutoCompleteBox.cs
@@ -2094,7 +2094,21 @@ namespace Avalonia.Controls
                 bool inResults = !(stringFiltering || objectFiltering);
                 if (!inResults)
                 {
-                    inResults = stringFiltering ? TextFilter(text, FormatValue(item)) : ItemFilter(text, item);
+                    if (stringFiltering)
+                    {
+                        inResults = TextFilter(text, FormatValue(item));
+                    }
+                    else
+                    {
+                        if (ItemFilter is null)
+                        {
+                            throw new Exception("ItemFilter property can not be null when FilterMode has value AutoCompleteFilterMode.Custom");
+                        }
+                        else
+                        {
+                            inResults = ItemFilter(text, item);
+                        }
+                    }
                 }
 
                 if (view_count > view_index && inResults && _view[view_index] == item)
diff --git a/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs b/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs
index b346fca330..c8bd289e54 100644
--- a/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs
@@ -105,6 +105,16 @@ namespace Avalonia.Controls.UnitTests
             });
         }
 
+        [Fact]
+        public void Custom_FilterMode_Without_ItemFilter_Setting_Throws_Exception()
+        {
+            RunTest((control, textbox) =>
+            {
+                control.FilterMode = AutoCompleteFilterMode.Custom;
+                Assert.Throws<Exception>(() => { control.Text = "a"; });
+            });
+        }
+
         [Fact]
         public void Text_Completion_Via_Text_Property()
         {