Would you take a look at this : http://dev.sencha.com/deploy/ext-4.0...rum/forum.html
As you can see, when you click on 'Preview Pane' button, the hidden panel will be shown at bottom of the panel. I need to do something like that but with 2 buttons and 2 hidden panels at the same place (bottom).
I think there is many correct ways how to solve your problem. E.g. you can create:
1) South panel {split: true, region: 'south', height: 100, itemId: 'xx', layout: 'fit', items: []}
2) Add two panels to this south panel (2nd will be hidden)
3) Add event - when you click button 1 you will show panel1, hide panel2 and backwards when you click 2nd button
Nothing difficult. Just show/hide south panel when you need it. You have two choices:
a) create hidden south panel
b) add panel when you need it and then test if panel already exists.
Nope in second case you will create new panel. You need test if this panel already exists or not. For you will be the best first case - just create south panels with two panels inside (2nd will be hidden).