GLPixmap
---------------
By: Janne Lf <jlof@mail.student.oulu.fi>
Description: 

Modification of rendering in a pixmap from gtkglarea dist to
test out the functionality of gtkgl--/gdkgl.


Events
---------------
By: Drake Diedrich <Drake.Diedrich@anu.edu.au>
Description:

Demo of event compression.

(This entire discussion is lifted from some X book I read years ago...)

A short demo intended to show the necessity of event compression.  

  ______________________         ______________________
 |                      |       |                      |
 |  Window              |_______|     Window           |
 |                      |       |                      |
 |______________________|       |                      |
            |    Demo window    |______________________|
            |                            |
 _____________________              _______________
|                     |            |               |
|   Window            |____________|  Window       |
|                     |            |_______________|
|_____________________|

To get the full effect of the demo, place one of the windows so that
it overlapse a good number of others (similar to shown above).  Raise 
each of the windows to the top so that only a small ammount of the demo 
window remains.  When you now raise the demo window to the top, you will 
get an output something like this...

draw() right count>0
draw() right count>0
draw() right count>0
draw() right count>0
draw() right

Each line represents one event call to redraw one of the window.
Instead of getting just one event when the window is brought forward,
we got 5.  As rendering GL can be expensive (under software simulation
or over an X connection), we must skip the expose events for all but
the last one.  To support this, an event structure has a field called
"count".  The count is the number of other expose calls pending from
a change in the window.  Therefore, since we only wish to do a redraw
on the last of these, we will skip all events whose count is greater
then zero.

(Other things that one can normally do to save time, include rendering to
a pixmap, instead of directly to the screen. Then copy back only
those portions that became exposed.)

Thanks to Drake Diedrich <Drake.Diedrich@anu.edu.au>
for contribution this demo. 

--Karl 
