I don't know if my problem is a XFCE-problem or a problem given by Ubuntu 13.10...
I have updated my Ubuntu 13.04 to 13.10. I use XFCE. After updating in some programs like bluefish or gedit the scroll wheel has no effect any more. I think all gnome programs make problems.
Firefox, libre office or thunar aren't affected. There is no problem using the scroll wheel.
Have you any ideas?
It's a known issue, see:
Thank, that worked.
Next time I should search the web in english not in german...