XDRIVER failing to repainting on some X11 Servers?

[Lawrence Houston]

On Wed, 13 Oct 1993, Olga Waupotitsch wrote:

> In info.grass.user you write:
> 
> >> Lawrence Houston,
> >> McGill University.
> >> 
> >wants to know why his Grass-monitor fails to repaint. For what it's
> >worth, on our system (RS 6000, AIX 3.2.2, X11R5) we can startup
> >Xwindows with the -bs (backing store) flag and force repainting.
> 
> >\_\_\_--\_----\_------\_-------------------- P. Martijn van Leusen --------- 
> > \_   \_ \_\_\_\_      \_        Dept of Pre- and Protohistoric Archaeology
> >  \_\_\_  \_ \_ \_      \_        University of Amsterdam, The Netherlands
> >   \_      \_    \_ \_\_ \_               martijn at scanner.frw.uva.nl
> >    \_------\_----\_--\_--\_\_\_\_--------------------------------------
> 
> Exacltly correct. The commented out code was making sure Grass monitor
> would run without backing store brovided by Xserver. So if you don't have
> backing store, uncomment the code I mentioned earlier.
> Sorry for the inconvenience.
> Olga

There should be NO need to comment out the code in "Seve_Xevent.c" which
supports those X11 Servers which do not support Backing Stores, as there
is already code in "Graph_Set.c" which queries the Server with the
"DoesBackingStore" Macro.  After which the "backing_store" variable is
tested and hence forward this code should not be executed for Servers
which are supporting Backing Stores, as witnessed by an absence of the
"Destroying old pixmap" Messages when the XDRIVER Window gets resized!  I
can not guarantee that this works will all Servers which support Backing
Stores, but the code is definitely required for those which do not. 

Lawrence Houston,
McGill University.