I recompiled gnome-terminal with debugging symbols and traced it in gdb. It seems it is not directly gnome-terminal's fault, but rather libgtk's or some other libgsomething's, which is now taking over the showing of the menu bar. I noticed that some other applications have ugly issues with their menu bar, like gconf-editor which has it appearing only after a few seconds. This would also partly explain why gnome-terminal's computing of window's dimension are wrong.
I recompiled gnome-terminal with debugging symbols and traced it in gdb. It seems it is not directly gnome-terminal's fault, but rather libgtk's or some other libgsomething's, which is now taking over the showing of the menu bar. I noticed that some other applications have ugly issues with their menu bar, like gconf-editor which has it appearing only after a few seconds. This would also partly explain why gnome-terminal's computing of window's dimension are wrong.