Simultaneous vertical/horizontal mouse wheel scrolling

[andrewl at acay.com.au]

Hi,

After installing the Mandrake xfce 4.2 rpms, it seems that mouse wheel 
scrolling behaviour has changed - previously the mouse wheel scrolled 
vertically when the pointer was in the application window, now it scrolls 
simultaneously horizontally and vertically (and if it's Mozilla, though the 
history also!).  Is there a way to configure this behaviour, and is this 
really a recent change?

Any pointers anyone?

Thanks in advance.

Andrew Lees.