grass on sgi: monitor problems

Ken Sibley ksibley at
Mon Jul 11 17:12:47 EDT 1994

> Carrie, 
> I don't know what causes your problem because I do not know the ins and outs of X-windows.
> But I have experienced similar behavior on a DECstation.  If I resize the grass monitor, I
> loose the graphics.  The only way to "retain" the image is to redraw it.  At least as far 
> as I have figured out.  Unless someone else out there can explain to us why this happens and
> suggest a solution, I would just try not to cover your graphics display.  Not much of a 
> solution, I know, but I will be listening for a better response along with you.
This discussion came up not too long ago so you may also want to check
the archives for more information from others.

I am not an expert, but I can give you some basic info on the problem.
You must use d.erase anytime you resize the graphics monitor and
then redraw.  The reason has to do with those fun little fifos again.
The graphics driver keeps all of the drawing information internal 
and only talks to X when a redraw, resize or repostion takes place.
This means that X does not really tell GRASS that the graphics window
has been resized.  It checks the size when you use d.erase.  It may
also now check when you redraw, but we teach our users to use d.erase
just to be sure (d.frame -e may be more appropriate in some cases).
This is why you must use the systems backing store rather than just
have a resource in GRASS for bringing the graphics monitor to the front.
This especially shows up when using DOS X emulators or some X terminals.

If you are now really confused then you know as much as the rest of us :-).
Some of these issues were around before X was so popular and have just
never been fixed.  Hopefully the tcltkgrass super view window will
help solve many of these kinds of problems.

Ken Sibley
USDA-SCS		"Hell, if you understand everything I say,
ksibley at   you'd be me!"  - Miles Davis

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