detecting the live user

[jwalker@crl.dec.com]

I'm trying to do some user monitoring research.  I need to
know, given a particular time interval, whether the person
used the mouse only, the keyboard only, or both (NOT
either).  Does anyone know whether there are existing
primitives that enable me to determine when the last
activity of a given type occurred?  I know about
tv:kbd-last-activity-time but that seems to be an inclusive
OR, which is the only case I'm not interested in right now.

Jan
jwalker@crl.dec.com