如何获得右击dijit.Menu被binding的层的id

<script language="JavaScript" type="text/javascript">
dojo.require("dijit.Menu");
dojo.require("dijit.ColorPalette");
dojo.require("dijit._Calendar");
dojo.require("dojo.parser"); // scan page for widgets and instantiate them
</script>
   
    <script language="Javascript" type="text/javascript">
        dojo.addOnLoad(function() {
            // create a menu programmatically
            function fClick() {alert("clicked!")};
            var prog_menu = new Array("prog_menu1","prog_menu2");
            var pMenu = new dijit.Menu({targetNodeIds:prog_menu});
            pMenu.addChild(new dijit.MenuItem({label:"Programmatic Context Menu", disabled:true}));
            pMenu.addChild(new dijit.MenuSeparator());
            pMenu.addChild(new dijit.MenuItem({label:"Simple menu item", onClick:fClick}));
            pMenu.addChild(new dijit.MenuItem({label:"Another menu item", onClick:fClick}));
            pMenu.addChild(new dijit.MenuItem({label:"With an icon", iconClass:"dijitEditorIcon dijitEditorIconCut", onClick:fClick}));
            var mItem = new dijit.MenuItem({label:"dojo.event clicking"});
            dojo.connect(mItem, "onClick", function(){alert("click! handler created via dojo.connect()")});
            pMenu.addChild(mItem);

            var pSubMenu = new dijit.Menu({parentMenu:pMenu, id:"progSubMenu"});
            pSubMenu.addChild(new dijit.MenuItem({label:"Submenu item", onClick:fClick}));
            pSubMenu.addChild(new dijit.MenuItem({label:"Submenu item", onClick:fClick}));
            pMenu.addChild(new dijit.PopupMenuItem({label:"Submenu", popup:pSubMenu, id:"progPopupMenuItem"}));
           
            pMenu.startup();
        });
    </script>

  <div id="prog_menu1" style="border:1px solid blue; padding:10px; margin:20px 0;">
            This div has a programmatic context menu on it that's different to the page menu.
        </div>
         <div id="prog_menu2" style="border:1px solid blue; padding:10px; margin:20px 0;">
            This div has a programmatic context menu on it that's different to the page menu.
        </div>

就如上边的.当在层prog_menu1,prog_menu2上右击,就会有menu出现,我想在menu中的一个子菜单中onclick,得到<div>层的id