improved batching behavior of text rendering

OpenRA.Game/Widgets/CheckboxWidget.cs

@@ -55,6 +55,8 @@ namespace OpenRA.Widgets
 						Color.White);
 				Game.chrome.lineRenderer.Flush();
 			}
+
+			Game.chrome.rgbaRenderer.Flush();
 			
 			base.Draw();
 		}

OpenRA.Game/Widgets/LabelWidget.cs

@@ -46,6 +46,7 @@ namespace OpenRA.Widgets
 					- new int2(textSize.X / 2, textSize.Y/2);
 			
 			Game.chrome.renderer.BoldFont.DrawText(Game.chrome.rgbaRenderer, Text, position, Color.White);
+			Game.chrome.rgbaRenderer.Flush();
 			Game.chrome.renderer.Device.DisableScissor();
 			base.Draw();
 		}

OpenRA.Game/Widgets/WidgetUtils.cs

@@ -59,10 +59,10 @@ namespace OpenRA.Widgets
 			sr.DrawSprite(ss[5], new float2(Bounds.Right - ss[5].size.X, Bounds.Top), "chrome");
 			sr.DrawSprite(ss[6], new float2(Bounds.Left, Bounds.Bottom - ss[6].size.Y), "chrome");
 			sr.DrawSprite(ss[7], new float2(Bounds.Right - ss[7].size.X, Bounds.Bottom - ss[7].size.Y), "chrome");
-			sr.Flush();
 
 			if (a != null) a();
 
+			sr.Flush();		// because the scissor is changing
 			r.Device.DisableScissor();
 		}
 	}