Success! Looks like we've fixed this one. According to our records the fix was applied for
Ext GWT Premium Member
Viewport scrolling issue in Firefox on GXT 2.2.6
We're running into a problem that appears exist in the current ExtGWT 2.2.6 code base and we're looking for a work around. The issue only exist in FF (it works as expected in IE).
Currently we're using Viewports to load our app. The problem first surfaced when we had a HTMLContainer in a BoarderLayout that needed to scroll because it had a lot of text in it (think of an e-mail client with a grid on one side and a reading/preview area on the other). In the HTMLContainer (in FF only) we are able to click on it to make sure it has the focus and then press the down arrow and the whole page shifts up by 10-15 pixels. Upon finding this we tried it elsewhere throughout other Viewports we render and found the same issue exist there as well.
To reproduce this bug in FF go to http://www.sencha.com/examples-2/#editablegrid, then click anywhere in the white space on the page and press the down arrow. You should see the entire page shift up by about 15 pixels.
Is this a known issue and is there any work around to prevent this from happening.
I moved this thread to the bugs forum so we can take a look at it. Thanks for reporting. There is currently no known workaround.
If this is a high priority issue for you, you should try to open a real support ticket in your ticket system.
Sencha - Support Team
For those who land on this later... The fix for this is adding absolute position to the __gwt_historyFrame This is how its done in the 3.x.