SuperBoxSelect in Extjs 4

I have downloaded SuperBoxSelect which is supported in Extjs3, but I want to use it in Extjs 4.

I have define class and extend it as needed in Extjs 4, and remove Ex.ns() and Ext.reg().

But when I run the code I got bellowed error.

Uncaught TypeError: Cannot read property 'superclass' of undefined

So what I need to do to use it in Extjs 4?

Code:

Ext.define('Ext.ux.form', {
    extend: 'Ext.ux.form.SuperBoxSelect',
    alias: '开发者_运维技巧widget.superboxselect',
    .....
    .....
});

---

Use this Ext.ux.form.field.BoxSelect-Intuitive-Multi-Select-ComboBox.

ExtJS3's plugin can't use in ExtJS4.

---

there is a 5.x framework component Ext.form.field.Tag, which does just that:

Ext.form.field.Tag

or aliased:

xtype: 'tagfield'