gtk2/gtk/ui/gtkdialog.ui

<interface domain="gtk40">
  <template class="GtkDialog" parent="GtkWindow">
    <property name="window-position">center-on-parent</property>
    <property name="type-hint">dialog</property>
    <child type="titlebar">
      <object class="GtkHeaderBar" id="headerbar">
        <property name="show-title-buttons">1</property>
      </object>
    </child>
    <child>
      <object class="GtkBox">
        <property name="orientation">vertical</property>
        <style>
          <class name="dialog-vbox"/>
        </style>
        <child>
          <object class="GtkBox" id="content_area"/>
        </child>
        <child>
          <object class="GtkBox" id="action_box">
            <style>
              <class name="dialog-action-box"/>
            </style>
            <child>
              <object class="GtkBox" id="action_area">
                <property name="hexpand">1</property>
                <property name="halign">end</property>
                <style>
                  <class name="dialog-action-area"/>
                </style>
              </object>
            </child>
          </object>
        </child>
      </object>
    </child>
  </template>
</interface>