kc.js

itemcontextmenu: function(tree, record, item, index, e, eOpts) {
    // Optimize : create menu once
    var position = e.getXY();
    var menu_grid = new Ext.menu.Menu({
        items: [{
            text: 'More details',
            handler: function() {
                console.log("Moreils");
            }
        }]
    });
    e.stopEvent();
    menu_grid.showAt(position);
}