Gtk.MenuShell.prototype.select_first

function select_first(search_sensitive:Boolean):void {
    // Gjs wrapper for gtk_menu_shell_select_first()
}

Select the first visible or selectable child of the menu shell; don't select tearoff items unless the only item is a tearoff item.

Since 2.2

search_sensitive: if true, search for the first selectable menu item, otherwise select nothing if the first item isn't sensitive. This should be false if the menu is being popped up initially.