I'm really not sure what's the deal with the non-smooth expand/collapse. It's something to do with the way the time works in a given browser. It seems to be better on some machines/browsers than others. We're using an Atlas Animation object internally - it controls changing the value from the max to the min, so something is slowing that guy down.
The brief display issue is something we've added some better support for in the refresh but the key here is to also set 'style="overflow:hidden"' on your panel in your web page. That should stop the initial flash.
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