[vile] Unfamiliar scroll bar operation in Ubuntu build of xvile - how to use it?

[Chris Green]

I have just upgraded my system to xubuntu 11.10 and, seeing that the
repository version of vile/xvile was pretty up to date I installed it. 

However it seems to have an odd (i.e. unfamiliar to me) scroll-bar set
up.  Can anyone tell me how it's supposed to work because I can't see
any way at the moment to simply drag the bar up and down to scroll the
text. 

What I see is a fairly normal looking scroll bar but when I hover the
mouse pointer over any part of the scroll bar the pointer changes to a
double headed arrow pointing up and down.

Aha, I see what's going on:-

    Button 1 - scroll down a chunk
    Button 3 - scroll up a chunk
    Button 2 - drag the scroll bar

The trouble is that I use a trackball and click and drag with button 2
is most awkward.

Is there any way I can change this behaviour without a d-i-y build of
xvile?

-- 
Chris Green