<extension
        point="org.eclipse.ui.popupMenus">
     <objectContribution
           adaptable="true"
           id="com.qualityeclipse.favorites.popUpMenu"
           objectClass="org.eclipse.core.resources.IResource">
        <action
              class="com.qualityeclipse.favorites.actions.AddToFavoritesActionDelegate"
              enablesFor="+"
              icon="icons/sample.gif"
              id="com.qualityeclipse.favorites.addToFavorites"
              label="Add"
              menubarPath="com.qualityeclipse.favorites.popupSubMenu/content"
              tooltip="Add the selected resource(s) to the Favorites view">
        </action>
        <menu
              id="com.qualityeclipse.favorites.popupSubMenu"
              label="Favorites"
              path="additions">
           <groupMarker
                 name="content">
           </groupMarker>
           <separator
                 name="additions">
           </separator>
        </menu>
     </objectContribution>
  </extension>

1.objectClass属性指定当用户点击什么类型的资源时，右键菜单可见

2.id="com.qualityeclipse.favorites.popupSubMenu"指定右键菜单的id

3.  <groupMarker
         name="content">
     </groupMarker>

用于在右键菜单中指定一个分组

4. <separator
        name="additions">
    </separator>

用于指定右键菜单的一个可扩展点，用于其它plugin扩展这个右键菜单

5.menubarPath="com.qualityeclipse.favorites.popupSubMenu/content"

用于指定这个action的Insertion Point.