The filter *.dbf does not work in Linux.
Fix (to add asterisk and dot ahead of second dbf):
...
fs.Type("*.dbf", "*.dbf");
...
I'm not sure if this works for windows and which one is the "correct" way to use in U++. Was it just a problem with example and my fix is correct, or the whole filter thing is broken in Linux and U++ FileSel requires fixing?