Sets @tooltip as the contents of the tooltip for the icon at
the specified position. @tooltip is assumed to be marked up with
the [Pango text markup language]PangoMarkupFormat.
Use %NULL for @tooltip to remove an existing tooltip.
See also gtk_widget_set_tooltip_markup() and
gtk_entry_set_icon_tooltip_text().
Sets @tooltip as the contents of the tooltip for the icon at the specified position. @tooltip is assumed to be marked up with the [Pango text markup language]PangoMarkupFormat.
Use %NULL for @tooltip to remove an existing tooltip.
See also gtk_widget_set_tooltip_markup() and gtk_entry_set_icon_tooltip_text().