Gtk.Widget:tooltip-markup
"tooltip-markup" String : Read / Write
Sets the text of tooltip to be the given string, which is marked up with the <link linkend="PangoMarkupFormat">Pango text markup language</link>. Also see Gtk.Tooltip.prototype.set_markup.
This is a convenience property which will take care of getting the tooltip shown if the given string is not null: Gtk.Widget:has-tooltip will automatically be set to true and there will be taken care of Gtk.Widget::query-tooltip in the default signal handler.
Since 2.12