Sets the icon of the tooltip (which is in front of the text) to be the icon indicated by gicon with the size indicated by size. If gicon is null, the image will be hidden.
a #GIcon representing the icon, or null
a stock icon size (#GtkIconSize)
Sets the icon of the tooltip (which is in front of the text) to be the icon indicated by gicon with the size indicated by size. If gicon is null, the image will be hidden.