gtk:button-icon-name (object)

object -- a gtk:button widget
name -- a string for an icon name, or nil

The accessor for the icon-name slot of the gtk:button class returns the icon name of the button, or adds a gtk:image widget with the given icon name as a child widget.

If the icon name has not been set the return value will be nil. This will be the case if you create an empty button with the gtk:button-new function to use as a container. If the button already contains a child widget, that child widget will be removed and replaced with the image.