In OpenGoo 1.6-rc, opening a mail in Firefox 3.5 or Opera 10.10 cause displays problems (text is partially hidden) with default theme, as you can see here.
It works well with Chromium (4.0.260.0 Ubuntu build).
Tested with Ubuntu 9.10.
It look like the problem is in this td balise :
<td class="coViewBody">
