I noticed that on PR2 when I focus field and click "return" button on screen keyboard it doesn't perform blur on this field, so I have to click hide keyboard button. I tested it using sencha 2.0 PR1 and it is fine. Below you can find code I used for testing (in fact much more configurations were tested - from placing every element in config, to Ext.define everything and add on initComponent).
I tried it on iPad 1gen.
Second thing is that I can't find if it's possible to post a form on click "return" button from screen keyboard using Sencha.