[news.eclipse.modeling.gmf] How to add a menu item on the context menu

[billgrand08@xxxxxxxxx (Bill Grand)]

I see that we can use the 
"org.eclipse.gmf.runtime.common.ui.services.action.contributionItemProviders" 
extension point, can someone give a example how to add a menu item on the 
context menu, I define as below, but it doesn't work(add a menu named 
"AssignToGlossaryMenu"), thanks.

   <extension
         id="ContributionItemProvider"
         name="ContributionItemProvider"
         
point="org.eclipse.gmf.runtime.common.ui.services.action.contributionItemProviders">
      <contributionItemProvider
            checkPluginLoaded="false"
            class="com.mine.actions.ContributionItemProvider">
         <Priority
               name="Lowest">
         </Priority>
         <popupContribution
               
id="org.eclipse.gmf.runtime.diagram.ui.DiagramEditorContextMenu">
            <popupMenuGroup
                  id="PopupMenuGroup"
                  path="/"
                  separator="true">
            </popupMenuGroup>
            <popupMenu
                  id="AssignToGlossaryMenu"
                  path="/PopupMenuGroup">
            </popupMenu>
            <popupAction
                  id="AssignToGlossaryAction"
                  path="/AssignToGlossaryMenu">
            </popupAction>
         </popupContribution>
      </contributionItemProvider>
   </extension>