After some fight with qmake and lrelease/lupdate, I've finally managed to allow translations in GePeS. I see no clear reason why QML translating is that poorly supported within Qt tools, however with some hacks it seems to be doable.
As usual with my software, besides using sources (Qt's translation files in this case), you can use translation server to do online translation. As there are only few words to translate, I hope some languages will be translated soon. Of course to give you good example, I've completed Czech translation immediately :-).
