maybe I´m about to demontsrate my stupidty (again).

I want to do "off-off-screen" rendering with GRX, huh, what??
Let me explain.

It all works almost fine for one time:
I do:

  GrSetDriver("memory gw 640 gh 400 nc 256");
  GrSetMode(GR_default_graphics);
  GrContext* root = GrCurrentContext();
  GrSetContext ( root );
  root = GrSaveContext( NULL );

  /* doing lots of drawing */
  /* ... */
  /* after a while, probing what has been drawn,(double-loop x,y): */
  c = (*GrCurrentFrameDriver()->readpixel)((GrFrame *)(&(root)->gc_frame), ((x)), ((y)) );
  /* => leads to all what is fine. */

This all works fine for one level of offscreen-drawing.

Now for the bisquit:

Beyond that, I would like to generate another GrContext out of the blue,
make some drawings on it, off-off-screen, so to speak,
and later do something like the following:
GrImage img_local = GrImageFromContext(ImageGrContext_out_of_the_blue);
GrImageDisplay(x, y, img_local);
to smash this image onto my root-GrContext.

The bisquit is this "ImageGrContext_out_of_the_blue":
When not in offscreen mode (that is, having said GrSetDriver("xwin...")), it all works great when doing:
ImageGrContext_out_of_the_blue = GrCreateContext(width,height,NULL,NULL);
Mainly because
GrCoreFrameMode()       (GrDriverInfo->sdriver.rmode)
leads to something usable (??).

But when being in offscreen-mode, GrCoreFrameMode() yields NULL.
This might be alright, but GrCreateFrameContext() depends on a
valid mode, thus returning NULL for the whole function, and
blocking all what should follow.

Later I tried to spoof this function with
ImageGrContext_out_of_the_blue = GrCreateFrameContext(19, ....);
(19 is the mode I need, it seems),
but this leads to SigSegv. later somewhere in the system.
 

Many thanks in advance.
greetings, Joe.

-- 
Joachim Euchner, Prozessrechnerverbund-Zentrale                            
Sekr.: MA 073, FSP-PV, Technische Universitaet Berlin      
Str. d. 17. Juni 136, 10623   Berlin, Deutschland          
Phone: [(+49|0)30]-314-21701   Fax: ..-21114                
Email: joe@prz.tu-berlin.de           
www:   www.prz.tu-berlin.de/~joe
"We're going up the river about 75 klicks above the 
Do Lung bridge."