Handler for the 'checkchange' event from an check item in this menu
@param {Object} item Ext.menu.CheckItem
@param {Object} checked The checked value that was set
function (item, checked) {
        var value = [];
        this.items.each(function(item){
            if (item.checked) {
                value.push(item.value);
            }
        });
        this.selected = value;

        this.fireEvent('checkchange', item, checked);
    }