GL multimap mode

[Martin Liversage]

While trying to use multimap mode I discovered that the window in
multimap mode would sometimes become garbled after a redraw. It seems
like this problem gets worse if there is a imakebackground process
(e.g. twilight). To test this I used a small program:

---------------------------------------------------------------------
#include <gl/gl.h>
#include <gl/device.h>

#if defined(ONEMAP)
# define NAME "Multimap"
#else
# define NAME "Onemap"
#endif

int main()
{
  long gid;
  short val;
  unsigned i;

  gid = winopen(NAME);
#if !defined(ONEMAP)
  multimap();
  gconfig();
  setmap(1);
#endif
  ortho2(0,10,0,10);

  qenter(REDRAW,gid);

  for (;;)
  {
    if (qread(&val) == REDRAW)
    {
      reshapeviewport();
      for (i = 0; i < 10; ++i)
      {
	color((i + 1)*25);
	rectfi(i,0,i + 1,10);
      }
    }
  }
}
---------------------------------------------------------------------

I executed the program and then reshaped and moved the window around
on the screen.

Very rarely, but still sometimes, the contents of the window would
become garbled.

Then I ran a program for drawing the root window (using
imakebackground()).

Now the multimap program would have its window contents garbled  more
often. This is naturally difficult to judge, but I think I'm right.

The problem persisted even after I killed the root window program. I
had to restart the NeWS server (e.g. log out and back in) to get back to
the first state where the problems is seen only very rarely.

When I ran the program in onemap mode (by defining ONEMAP) the problem
disappeared.

What is going on? Am I doing something wrong or is this a GL/NeWS bug?
I have Irix 3.2.

Martin Liversage <operator at iris.kth.dk>
Royal Dental College Copenhagen
Department of Pediatric Dentistry
Norre Alle 20
DK-2200 Kobenhavn N