why doesn't Xpmac like my mouse?

["John R. MacPhail" <jrmacpha@math.uwaterloo.ca>]

I'm on Potato, with XFree86-Xpmac-3.3.6-8a, and a two-line ~/.xserverrc,

    #!/bin/sh
    exec Xpmac -noaccel

This gives me an X server that appears to work fine, except that my
mouse is ignored completely.  Suggestions?

Here is further data.  Earlier experience on MkLinux and LinuxPPC was
that the -noaccel option was necessary; otherwise, the machine froze.
This somehow comes from using a Mach64 card (or whatever it is inside
the beige G3) together with my ancient Apple model M1212 monitor.
This monitor runs 640x480 at 67 Hz, which evidently is slightly
unusual, and does seem to increase my opportunities for messing things
up.  It does not look as though either Potato's FBDev or the current
X11R4 prerelease supports unaccelerated Mach64.  That is why I am
falling back on Xpmac.

Installing Xpmac was easy: I ran alien on *.ppc.rpm and then dpkg -i
on the deb.  My gpm, in its default configuration, works fine outside
X.  Killing gpm before launching X did not seem to change anything.
My keyboard is an M2980 (`AppleDesign Keyboard') and the mouse is a
single-button ADB II.  I have /dev/mouse as a symlink to
/dev/adbmouse.

It is conceivable that I may have messed something up, particularly as
X has got me quite confused.  Here is a specific question: the
`QuickStart to XFree86 Setup' recommends XF86Setup -- do I have any
hope of being able to run that?  And, if so, where should I look for
it?

---
John