evad: You get the third level with the Fn key, not with the Ctrl!!!

I tried to reconfigure the Polish keyboard "my way". I had no troubles setting the dead keys for the requested characters... Three worked just fine (dead_abovedot, dead_ogonek and dead_acute), but the fourth didn't (dead_stroke). So you could use those (to avoid the uncomfortable typing of ą) but still have to map something to get the the Ł

Maybe's just this bug: https://bugs.maemo.org/show_bug.cgi?id=2259. Should we fill it for Fremantle?

About the fourth level: have you tried to map Shift+Fn as fourth level? That way you'll keep the virtual keyboard and still get an additional level...