Looks like we can't reproduce the issue or there's a problem in the test case provided.
Ext JS Premium Member
Agreed - we really need this fix backported to 4.0.X. Not reasonable to have to wait for production 4.1 (and the necessary time spend upgrading my application)
Originally Posted by Burke
Premium users can request a patch at http://support.sencha.com/
Google released an update to Chrome this morning (v 18.0.1025.151) that fixes the crash.