After having went through the GWT StockWatcher tutorial, I find a small UI problem, as shown in this image

When I change the background color of body from white to green manually, a small white square becomes visible. I have seen several examples of this, so I’m pretty sure it is not a programming error that I have made. On the contrary, it seems to stem from one of the hidden iframes inserted by GWT, since it disappears when I delete the iframe or all of it’s contents.
Also it seems to be a Chrome- or Chrome-GWT-plugin specific issue, since I could not replicate it in Firefox.
Does anyone know the cause/fix of this problem?
Disclaimer: I just tried this and it seems to work but its not very well tested.
The body had a margin of 8px on all sides. I set it to 0px with
This seemed to have removed the problem. If you wanted the margin you would have to add it back to a nested element inside your body.