Stubs for TitleBarHeight Hint.

src/Avalonia.DesignerSupport/Remote/PreviewerWindowImpl.cs

@@ -140,5 +140,9 @@ namespace Avalonia.DesignerSupport.Remote
         public void SetExtendClientAreaChromeHints(ExtendClientAreaChromeHints hints)
         {            
         }
+
+        public void SetExtendClientAreaTitleBarHeightHint(double titleBarHeight)
+        {            
+        }
     }
 }

src/Avalonia.DesignerSupport/Remote/Stubs.cs

@@ -154,6 +154,10 @@ namespace Avalonia.DesignerSupport.Remote
         {
         }
 
+        public void SetExtendClientAreaTitleBarHeightHint(double titleBarHeight)
+        {
+        }
+
         public IPopupPositioner PopupPositioner { get; }
 
         public Action GotInputWhenDisabled { get; set; }

src/Avalonia.Native/WindowImpl.cs

@@ -114,6 +114,10 @@ namespace Avalonia.Native
         {
         }
 
+        public void SetExtendClientAreaTitleBarHeightHint(double titleBarHeight)
+        {
+        }
+
         public void ShowTaskbarIcon(bool value)
         {
             // NO OP On OSX

src/Avalonia.X11/X11Window.cs

@@ -1051,6 +1051,10 @@ namespace Avalonia.X11
         {
         }
 
+        public void SetExtendClientAreaTitleBarHeightHint(double titleBarHeight)
+        {
+        }
+
         public Action GotInputWhenDisabled { get; set; }
 
         public void SetIcon(IWindowIconImpl icon)