Tutorial:Extending Ext Class

Objective   Intended resulting IconCombo Let's create an extension of Ext.form.Combobox that will display icons in front of texts. Such combo could be useful, for example, for selection of countries when we'd have the country flag followed by the country name. Let's give our extension name Ext.ux.IconCombo.

http://www.sencha.com/learn/Tutorial:Extending_Ext_Class