The top menu is shown by default on all backend pages. To add menu items simply add them to the Acl. But you can further modify the menu and add any other custom functionality by implementing your own menu class.

This example adds a second combobox similar to the change user combobox:

var Menu = Ext.extend(Kwf.Menu.Index,
    controllerUrl: '/admin/misc/menu', //optional, to add additional data to response
    loadMenu: function(response, options, result)
        Menu.superclass.loadMenu.apply(this, arguments);
        if (Kwf.userRole == 'admin') {
            var changeXxx = new Kwf.Form.ComboBox({
                store: {
                    url: '/admin/misc/change-xxx/json-data'
                mode: 'remote',
                triggerAction: 'all',
                typeAhead: true,
                width: 60,
                listWidth: 60,
                selectOnFocus: true,
                minChars: 2,
                emptyText: trl('Xxx'),
                tpl: new Ext.XTemplate(
                        '<tpl for=".">',
                        '<div class="x-combo-list-item">',
            changeXxx.on('render', function(combo) {
                if (result.changeXxx) { //from custom menu action
            }, this, {delay: 10});
            changeXxx.on('select', function(combo, record, index) {
                    url: '/admin/misc/change-xxx/json-change-xxx',
                    params: { xxx: },
                    success: function() {
                        location.href = location.href;
                    scope: this
            }, this);
            this.insert(this.items.indexOfKey('currentUser')-1, changeXxx);
Ext.reg('', Menu);