This method is called when a mouse button is clicked twice in rapid succession.
| Parameter | Description | 
|---|---|
| button | which mouse button that was clicked, can be MOUSE_LEFT, MOUSE_RIGHT, or MOUSE_MIDDLE | 
| x | mouse x position when clicked | 
| y | mouse y position when clicked | 
This is a protected virtual method. It can only be used by declaring it in a custom widget.