I am having this problem and I am able to reproduce it on the samples page.

Repro steps:

1. Go to https://examples1.ext.net/ (FireFox)
The initial Home tab has a GridPanel "Recent SVN Commits"
2. Move the grid's scrollbar down so that it is no longer at the top
3. Open up any other tab from the samples
4. Switch back to the Home tab.
The scrollbar has reset to the top.

Please advise