Accessor of the app-paintable slot of the gtk-widget class.
The gtk-widget-app-paintable slot access function returns true if the widget will paint on the widget. It determines whether the application intends to draw on the widget in an "draw" handler.
The (setf gtk-widget-app-paintable) slot access function sets whether the application intends to draw on the widget in a "draw" handler.
This is a hint to the widget and does not affect the behavior of the GTK+ core; many widgets ignore this flag entirely. For widgets that do pay attention to the flag, such as gtk-event-box and gtk-window, the effect is to suppress default themed drawing of the widget's background. Children of the widget will still be drawn. The application is then entirely responsible for drawing the widget background.
Note that the background is still drawn when the widget is mapped.