Retrieves the GdkPaintable used for the icon.
If no GdkPaintable was used for the icon, %NULL is returned.
Icon position
A GdkPaintable, or %NULL if no icon is set for this position or the icon set is not a GdkPaintable.
See Implementation
Retrieves the GdkPaintable used for the icon.
If no GdkPaintable was used for the icon, %NULL is returned.