I have been having the same problem.  Attached is my XWin.log.

To clarify:  2 screens.  Any movement of a window makes it enter a state
where it is all white when on the right screen, and will display normally on
the left screen, except for the cursor.

I miss my rootless, multiwindow display!

Thanks,
Dan

Re:

 Ben Jackson wrote:


I have been (successfully) using XWin with -multimonitor -multiwindow
recently. However, since upgrading to the latest release (via setup.exe -
4.2.0-3)

4.2.0-3 of what? The only really useful version number is the version of the
XFree86-xserv package, and the current version is 4.3.0-49. Update tomorrow
and see how it works.

Harold