Another comparison - Opera 9.64 and Firefox 2 (Intrepid)... Opera behaves similarly as FF3, FF2 seems to display more colors, though xwininfo showed equal depth (16) after clicking on each of windows. (As far as I know xorg.conf in tested 9-yrs old IBM comp doesn't contain color depth at all for some reason but both xdpyinfo and xwininfo showed 16.)
Another comparison - Opera 9.64 and Firefox 2 (Intrepid)... Opera behaves similarly as FF3, FF2 seems to display more colors, though xwininfo showed equal depth (16) after clicking on each of windows. (As far as I know xorg.conf in tested 9-yrs old IBM comp doesn't contain color depth at all for some reason but both xdpyinfo and xwininfo showed 16.)