Hi,
I use clearlooks engine and I've set the radius to 0 because it gives me the best look in openoffice and firefox (If text fields are rounded there are white areas in cornes). But when radius is set to 0, then text fields in oppenoffice, firefox and some other apps (sometimes midori) get a diagonal line.
Here's a screenshot of the bug: http://dl.dropbox.com/u/195714/Screenshot.png.