Sets the icon of the tooltip (which is in front of the text) to be the icon indicated by @icon_name with the size indicated by @size. If @icon_name is %NULL, the image will be hidden.
an icon name, or %NULL
See Implementation
Sets the icon of the tooltip (which is in front of the text) to be the icon indicated by @icon_name with the size indicated by @size. If @icon_name is %NULL, the image will be hidden.