Gtk.Image.new_from_icon_set

function new_from_icon_set(icon_set:Gtk.IconSet, size:Number):Gtk.Widget {
    // Gjs wrapper for gtk_image_new_from_icon_set()
}

Creates a Gtk.Image displaying an icon set. Sample stock sizes are #GTK_ICON_SIZE_MENU, #GTK_ICON_SIZE_SMALL_TOOLBAR. Instead of using this function, usually it's better to create a Gtk.IconFactory, put your icon sets in the icon factory, add the icon factory to the list of default factories with Gtk.IconFactory.prototype.add_default, and then use Gtk.new_from_stock. This will allow themes to override the icon you ship with your application.

The Gtk.Image does not assume a reference to the icon set; you still need to unref it if you own references. Gtk.Image will add its own reference rather than adopting yours.