When i press the tab button, then appear a white square that is annoying for me in my app. That white square appears in the bottom left of web page, only in Chrome Web Browser. In Firefox it's ok. I use ExtGWT 2.2.5.
Can't reproduce this on http://www.sencha.com/examples/explorer.html#basictabs which suggests this is due to your own css or other behavior. Can you post an entrypoint that demonstrates the issue, using the 2.2.5 jar and resources?