Netscape doesn't show the frames right. The URL above is a testsite for you. I made a frameset with 50,50,* pixels but Netscape only shows 48,48,*. If you change the size of the window it only gets worse. There is a screenshot to show you the difference between Netscape and e.g. Explorer.
Reassigning frameset/iframe bugs to Eric.
[TESTCASE] This seems to work for me. Using the following test case: http://www.bath.ac.uk/%7Epy8ieh/internet/projects/mozilla/frameheight.html ...it seems to me that Mozilla is correctly sizing the frames. Marking WORKSFORME. MatthiasW@u-planet.de: Could you check that the bug you reported is fixed in the latest builds please?