I create simple toolbar with menu and for all item added context menu. When I click to Menu and choose one of item from 'another menu' and click right button - the context menu is appear. When I click right button on another item the context menu appear behind the menu. Is it a bug or I doing something wrong?

Code:
Ext.onReady(function() {
    Ext.QuickTips.init();
    var views = new ViewsMenu();
});


function ViewsMenu() {
    this.init();
}

ViewsMenu.prototype = {
    init: function() {

        var anotherMenu = new Ext.menu.Menu({
            items:[
                {text: 'one'},
                {text: 'two'},
                {text: 'three'}
            ]
        });

        var menu = new Ext.menu.Menu({
            id: 'mainMenu',
            style: {
                overflow: 'visible'
            },
            items: [
                {text: 'One'},
                {text: 'Two'},
                {text: 'Three'},
                {
                    text: 'Another menu',
                    menu: anotherMenu
                }
            ]
        });

        var menus = [anotherMenu];
        menus.push(menu);
        for (var k = 0; k < menus.length; k++) {
            var m = menus[k];
            if (m.items) {
                for (var i = 0; i < m.items.length; i++) {
                    var item = m.items.itemAt(i);
                    if (item.rendered) {
                        item.getEl().on('contextmenu', this.onContextMenu, item);
                    } else {
                        item.on('render', function(o) {
                            o.getEl().on('contextmenu', this.onContextMenu, o);
                        }, this);
                    }
                }
            }
        }

        var tb = new Ext.Toolbar();
        tb.render('toolbar');

        tb.add({
            text:'Menu',
            menu: menu  
        });

        tb.doLayout();
    } ,

    onContextMenu : function(e, el) {
        e.preventDefault();

        var item = this;
        var id = 'views-saved-context-menu';
        var contextMenu = Ext.menu.MenuMgr.get(id);
        if (contextMenu) {
            contextMenu.destroy();
        }

        contextMenu = new Ext.menu.Menu({
            id : id,
            allowOtherMenus : true,
            items: [
                {
                    text:'Remove',
                    scope: this
                }
            ]
        });

        contextMenu.showAt(e.getXY());
    }
}