GtkIconSet. A GtkIconSet represents a single icon
in various sizes and widget states. It can provide a GdkPixbuf
for a given size and state on request, and automatically caches
some of the rendered GdkPixbuf objects.gtkIconSetNew()GtkIconSet] a new GtkIconSetgtkWidgetRenderIcon instead of
using GtkIconSet directly. The one case where you'd use
GtkIconSet is to create application-specific icon sets to place in
a GtkIconFactory.