Gtk.Tooltip.prototype.set_custom

function set_custom(custom_widget:Gtk.Widget):void {
    // Gjs wrapper for gtk_tooltip_set_custom()
}

Replaces the widget packed into the tooltip with custom_widget. custom_widget does not get destroyed when the tooltip goes away. By default a box with a Gtk.Image and Gtk.Label is embedded in the tooltip, which can be configured using Gtk.set_markup and Gtk.set_icon.

Since 2.12