fixes: Warnings CS0219 and CS0168

src/Avalonia.DesignerSupport/Remote/HtmlTransport/HtmlTransport.cs

@@ -25,7 +25,6 @@ namespace Avalonia.DesignerSupport.Remote.HtmlTransport
         private AutoResetEvent _wakeup = new AutoResetEvent(false);
         private FrameMessage _lastFrameMessage = null;
         private FrameMessage _lastSentFrameMessage = null;
-        private RequestViewportResizeMessage _lastViewportRequest;
         private Action<IAvaloniaRemoteTransportConnection, object> _onMessage;
         private Action<IAvaloniaRemoteTransportConnection, Exception> _onException;
         
@@ -177,6 +176,7 @@ namespace Avalonia.DesignerSupport.Remote.HtmlTransport
         
         public void Dispose()
         {
+            _disposed = true;
             _pendingSocket?.Dispose();
             _simpleServer.Dispose();
         }

src/Avalonia.X11/X11Window.Ime.cs

@@ -33,8 +33,6 @@ namespace Avalonia.X11
                         && ((int)(style & XIMProperties.XIMStatusNothing) != 0))
                     {
                         XPoint spot = default;
-                        XRectangle area = default;
-
 
                         //using var areaS = new Utf8Buffer("area");
                         using var spotS = new Utf8Buffer("spotLocation");

src/Skia/Avalonia.Skia/Gpu/OpenGl/GlSkiaGpu.cs

@@ -66,7 +66,7 @@ namespace Avalonia.Skia
                 _canCreateSurfaces = true;
                 return surface;
             }
-            catch (Exception e)
+            catch (Exception)
             {
                 Logger.TryGet(LogEventLevel.Error, "OpenGL")
                     ?.Log(this, "Unable to create a Skia-compatible FBO manually");