Comment 5 for bug 431922

Fabio, why change the bug to invalid? It is totally valid. The dead-stroke key is a new addition to X11, and some problems were to be expected. Saying the problem is not there will not fix KDE and Gnome applications which now can't handle it.
Have you actually tried it? You MUST use fi_FI.UTF-8 locale and the Finnish Kotoistus (default) keyboard layout, since it's the only one which currently has it configured. If you use xev, it will work. (E.g. Alt-Gr+'§' and 'o' produces 'ø'. '§' is usually on the same key with ` on the US keyboard.) xev uses X11 directly, skipping gnome and KDE systems. The bug is somewhere within the KDE and Gnome systems. Doing the same will produce 'o' in broken applications.
If you have a question, please ask.