Not sure if this is a bug or not, but thought I'd share since I had a problem and was able to work around. In a nutshell, I was creating a flash object using SWFObject bound to a div residing in an east panel PRIOR to creating the overall ViewPort layout. I had a heck of a time trying to figure out why I couldn't address the flash object with JS in IE (works in Firefox) like I normally do. After doing a few hours of debugging, I determined that the problem was due to the order of events -- simply moving the SWFObject creation AFTER creating the ViewPort effectively resolved the problem.
Not sure if this is a bug or not (or if I'm just being stupid), but I thought I'd share. Didn't have this problem with Ext 1.x, so it's probably noteworthy.