Several menuitems can be grouped together. The menuitems in the same group has the same value of name attribute. The click on the menu item selects it. The further behaviour depends on the value of type attribute.

If the type is equal to "radio", only one member of the group can be simultaneously selected. A selection of a new item automatically unselects the original one.

<?xml-stylesheet href="css1.css" type="text/css"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
align="vertical" >
     <menubar>
          <menu value="AAA">
               <menupopup>
                    <menuitem type="radio" name="gr1" value="aaa"/>
                    <menuitem type="radio" name="gr1" value="bbb"/>
                    <menuitem type="radio" name="gr1" value="ccc"/>
                    <menuseparator/>
                    <menuitem type="radio" name="gr2" value="111"/>
                    <menuitem type="radio" name="gr2" value="222"/>
                    <menuitem type="radio" name="gr2" value="333"/>
               </menupopup>
          </menu>
     </menubar>
</window>

xul2.xul

If the type is equal to "checkbox", several members of the group can be simultaneously selected.

<?xml-stylesheet href="css1.css" type="text/css"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
align="vertical" >
     <menubar>
          <menu value="AAA">
               <menupopup>
                    <menuitem type="checkbox" name="gr1" value="aaa"/>
                    <menuitem type="checkbox" name="gr1" value="bbb"/>
                    <menuitem type="checkbox" name="gr1" value="ccc"/>
                    <menuseparator/>
                    <menuitem type="checkbox" name="gr2" value="111"/>
                    <menuitem type="checkbox" name="gr2" value="222"/>
                    <menuitem type="checkbox" name="gr2" value="333"/>
               </menupopup>
          </menu>
     </menubar>
</window>

xul3.xul

The checked attribute equal to "true" selects the item at the startup

<?xml-stylesheet href="css1.css" type="text/css"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
align="vertical" >
     <menubar>
          <menu value="AAA">
               <menupopup>
                    <menuitem type="radio" name="gr1" value="aaa" checked="true"/>
                    <menuitem type="radio" name="gr1" value="bbb"/>
                    <menuitem type="radio" name="gr1" value="ccc"/>
                    <menuseparator/>
                    <menuitem type="checkbox" name="gr2" value="111"/>
                    <menuitem type="checkbox" name="gr2" value="222" checked="true"/>
                    <menuitem type="checkbox" name="gr2" value="333" checked="true"/>
               </menupopup>
          </menu>
     </menubar>
</window>

css1.css

The default Mozilla CSS is used.

@import url(chrome://global/skin);