XDRIVER failing to repainting on some X11 Servers?

[Lawrence Houston]

GRASS Users:

We recently observed a problem with GRASS 4.1's XDRIVER (Spring 1993 -
Patch Level #1) as it runs on some of our X11 Servers and but not others. 
Hoping that some "nice" GRASS User(s) might be able to provide an
explaination for a problem with failing to repaint displayed images after
being covered partially or fully by another windows.  With the binaries
running on a either of our two SUN SPARCstations, the failure to repaint
has been observed on two X-Servers: SunSofts's Interactive UNIX 3.0.1
(X11R4/Motif 1.1.1) and NCD's PC-Xware 1.0 running under Windows 3.1. 
Also tried the new Static Version of XDRIVER (September 14, 1993) which is
now availble on CERL's FTP Server and noticed no change. 

Repainting is observed on the SPARC's own System Consoles and on a MACX
Server (X11R4) with the GRASS 4.1 Code and on both the Interactive UNIX
and PC-Xware Servers when the same operations are performed under GRASS
4.0 (Summer 1991)!  Does this imply a change in XDRIVER's Code between
GRASS 4.0 and 4.1, or some subtle X-Server Configuration differences which
are only showing up with the newer code.  Can anyone hazard a guess or
know what differences in X-Servers could produce such differences? 

Lawrence Houston,
McGill University.