protected virtual void OnCanvasGUI()
{
GUI.BeginClip(clipRect);
GlobalMousePosition = Event.current.mousePosition;
Rect r = new Rect(Vector2.zero, clipRect.size);
RootCanvas.LocalRect = r;
ScaledCanvas.LocalRect = r;
RootCanvas.OnCalculateGlobalRect(true, r);
OnResized();
RootCanvas.OnGUI(r);
OnPainted();
GUI.EndClip();
}