Sets icon as the widget used as icon on button. If icon_widget is null the icon is determined by the #GtkToolButton:stock-id property. If the #GtkToolButton:stock-id property is also null, button will not have an icon.
the widget used as icon, or null
Sets icon as the widget used as icon on button. If icon_widget is null the icon is determined by the #GtkToolButton:stock-id property. If the #GtkToolButton:stock-id property is also null, button will not have an icon.