UIHANDLER OnMouseDown

Called when the user presses a mouse button overtop a mouse-enabled Frame. (self, button)

Arguments

 * self : - The widget on which the mouse button was pressed.
 * button : - "LeftButton", "RightButton", "MiddleButton", "Button4", "Button5", ..., "ButtonN"

Details

 * and controls whether OnMouseDown fire; however, setting OnMouseDown will implictly trigger.