apps/graphics/nxwidgets: CWidgetControl::handleLeftClick now returns a value to indicate if the click was actually processed or not. CWidgetControl::pollMouseEvents: Correct return value.
apps/graphics/twm4nx: CBackground::event(): Implement logic to handle a left click on the background and to bring up the main Menu. CWindowEvent: Extend message to distinguish between keyboard and mouse input. Mouse position and buttons now accompany the mouse input data. CMenus: Add methods to query and control the visibility of the menu.