Scrolling in the transition window seems to scroll in the background window in some occasions

It seems that when a user clicks on a transition which brings up a transition window with a field which has enough items to make it scrollable, the interaction with this field can sometimes affect the background window as well. I was able to reproduce this on FireFox, Safari, and Chrome on the Mac OS.

I have attached a JIRA 4.2.1 XML backup to this ticket to simplify the repro steps:

• import the XML
• login with username rick, password jira
• view issue AUDIO-10
• scroll all the way down to the bottom on the main page so that the ticket details are no longer showing in the screen and only the comments appear
• click Resolve Issue
• click Fix Version and select something from the top of the list (ie 1, 1.1, 1.2)

As soon as the Fix Version is clicked upon, you should notice that the background screen scroll up a bit even though it should be inactive at this point. This is frustrating for users who are viewing comments at the bottom of the page who are automatically scrolled to the top once they go through a transition.