Fix the StatusStripSizingGrip.

Author: KlausLoeffelmann

src/System.Windows.Forms/System/Windows/Forms/Controls/ToolStrips/ToolStrip.cs

@@ -3636,6 +3636,7 @@ protected override void OnPaintBackground(PaintEventArgs e)
 
         Graphics g = e.GraphicsInternal;
         GraphicsState graphicsState = g.Save();
+
         try
         {
             using (Region? transparentRegion = Renderer.GetTransparentRegion(this))
@@ -3647,6 +3648,12 @@ protected override void OnPaintBackground(PaintEventArgs e)
                 }
             }
 
+            if (Renderer.RendererOverride is ToolStripRenderer renderer)
+            {
+                renderer.DrawToolStripBackground(new ToolStripRenderEventArgs(g, this));
+                return;
+            }
+
             Renderer.DrawToolStripBackground(new ToolStripRenderEventArgs(g, this));
         }
         finally