TextValidator problem

I'm really sorry, but sometimes I feel just I'm a little bit dumb... and 
this is the case. I'm stiil using the TextValidator class. If I use the 
standard filtering options much of the characters normally used are 
filtered out. The Wx::FILTER_ALPHANUMERIC option filters out anything 
which is not [a-z], [A-Z] or [0-9]. It would be nice to use dots, bars 
and underscores too, so I thought to call the set_includes method, but 
with no result. Can anyone tell me which kind of parameter should I pass 
to set_includes? Can anyone give me few lines of working code?
Thanks in advance to anyone
Luciano