I’ve just run into a problem with laying a page containing a textarea.
I set it up using a Firefox window with a 1024*768 client area on Windows XP, but when I looked at it on Linux (Centos) the rest of the page ran off the bottom, even though everything should have been in the same position. Turns out that the Windows Mozilla is making the box 5 rows deep, as requested, but the Linux version is allocating space for scrollbars that aren’t needed.
Both are running Firefox 2.0.0.14, so there must be some difference in the underlying rendering libraries.