To get the desired behavior, edit /usr/share/X11/xkb/symbols/nokia_vndr/rx-51 (as root, so be careful!), look for your national keymap (in my case xkb_symbols "de") and change the line Code: key <LEFT> { [ period, comma, comma, comma ] }; into Code: key <LEFT> { [ period, period, comma, comma ]}; Then do Code: setxkbmap de (or for Polish: ... pl), and see whether you are happy with the new keyboard mapping. Don't reboot before you have checked that everything is all right, and also, if you make backups of the rx-51 file, put them in your home directory, not in the same directory where the system file is! EDIT: just looked up the Polish entries in rx-51 and found that they don't have period and comma where the German keyboard has them, so my instructions are good for the German, Portuguese/Spanish, Swiss, Italian, Czech, and Nordic versions only. For a general how-to see the wiki on keyboard remapping!
key <LEFT> { [ period, comma, comma, comma ] };
key <LEFT> { [ period, period, comma, comma ]};
setxkbmap de