There seem to be several problems with fluxbox's integrated key grabber. 1. It doesn't behave as specified in the manual: One cannot specify all emacs style key chains, as stated in the manual. i.e. "Mod 4 x k" does actually not define mod4+x - k, but mod4+x - mod4+k. 2. It swallows a few charakters of my input after changing the window focus via Mod4 n : NextWindow. 3. This is not a bug but a minor inconsitency: The Keyword for the spacebar in the keys file is 'space', lowercase, while all other special keys begin with an uppercase. Reproducible: Always Steps to Reproduce: 1.see above 2. 3.
Please file a bug upstream for these. None of them are thing I can fix easily myself.