Ext js - Dynamically changing content of Tab in a TabPanel

I have an (Ext JS) tab panel where the hidden tabs aren't loaded at all upon initial instantiation, (the only thing I set is the title).

Upon 'activation' of a tab I want to call a method , which then instanstiates a new FormPanel/GridPanel and put this content into the tab.

Can someone point me to a code example or give me tips on how to do开发者_高级运维 this?? Thanks so much!

Just build a new panel and add it to the activated tab. Then call doLayout().

listeners: {
    activate: function(panel) {
        var formPanel = ....
        panel.add(formPanel);
        panel.doLayout();
    }
}