I also use vertically-stacked dual monitors, however I do not see the odd maximisation behaviour. I suspect it is significant that the two screens have the same width, but different heights (1280x800, 1280x1024).
However, I do see the issue with maximised windows in the secondary screen disappearing under the title bar. This appears to be broadly similar to #707346 (the same issue, but in gnome).
I also use vertically-stacked dual monitors, however I do not see the odd maximisation behaviour. I suspect it is significant that the two screens have the same width, but different heights (1280x800, 1280x1024).
However, I do see the issue with maximised windows in the secondary screen disappearing under the title bar. This appears to be broadly similar to #707346 (the same issue, but in gnome).