gtk-tooltip-set-icon-from-gicon (tooltip gicon size)

tooltip -- a gtk-tooltip widget
gicon -- a g-icon representing the icon, or nil
icon-size -- a icon size of type gtk-icon-size

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 icon-size. If gicon is nil, the image will be hidden.