[dwm] Focus follows mouse

Hi,

At the time I switched from wmii back to dwm I was evaluating couple of
other WM from the family and I liked a feature I cannot currently tell
where it was (but I suspect it was Xmonad): switch off the
focus-follows-mouse behaviour.

Can anybody give a sketch how to achieve this in dwm (or give a hint where
to look at in the source)?

Thanx in advance!

-- 
 cheers
 stanio_