testing-repository/Gtkmm4/gtk144_gtkui6/res/context_menu.xml

<?xml version="1.0" encoding="UTF-8"?>
<interface>
    <menu id="context_menu">
        <section>
            <item>
                <attribute name="label">About</attribute>
            </item>
            <item>
                <attribute name="label">Customize</attribute>
            </item>
        </section>
    </menu>
</interface>