Hi all!
Yes, that is a problem. It seems that you can just assign a function without a parameter to a key or an event, e.g.
on_p = do_this;
And NOT
on_p = do_this(7);
That's a pity but it might explain why there are almost no functions in the templates (at least I found none so far) which works with a parameter...
If anyone finds a way to workaround this without defining a function for each call like it was done in the posting, please tell. 
Gnometech