Transparent animated gifs appear to be rendered with a black background, rather than with a black background, rather than transparent. I just checked this against Netscape 6.01, which appears to operate as expected.

Any idea why this might be so?

Thanks, Al Folsom

This was about Mozilla's biggest bug for close to two months now, and it was just fixed a few days ago. This does not work correctly in Netscape 6.1 PR1, nor the current k-meleon build, but it should be fixed for the next versions of both.