glxSwapBuffers in render thread with compositors missing update

[Roland Plüss]

The special situation is this:
- A toolkit driven application (FOX-ToolKit in this case)
- Render window is "injected" into the framework (so this means no
influence to X11 event loop handling of the application)
- Main Thread: Does everything not touching OpenGL (in particular has no
GL context assigned nor created)
- Render Thread: Does all OpenGL related rendering on a separate Display
connection
- glXSwapBuffers: called during synchronization time when both threads
get in touch with each other

In general this situation works. I can have multiple windows in the
toolkit all of which are rendered sequentially in the render thread and
display updates properly.

The problem now is if a Compositor comes into play and today this seems
to be omni-present. With the compositor enabled the glXSwapBuffers is
sort of "ignored" by the compositor in the main thread. Basically the
compositor updates the first rendered frame and all consequtive
glXSwapBuffers are ignored. If I disable the compositor though all
glXSwapBuffers work splendid.

My conclusion is that glXSwapBuffers in the second thread does properly
notify X-Server about the swap of the front and back buffer but the
compositor is somehow left out in the dark.

My question is now does somebody know how I can force an update onto the
compositor? I tried already sending an Expose event with XSendEvent to
the main thread display connection but this had no effect. I guess I
have to get more creative to kick the compositor in the butts?

-- 
Mit freundlichen Grüssen
Plüss Roland

Leader und Head Programmer
- Game: Epsylon ( http://www.indiedb.com/games/epsylon )
- Game Engine: Drag[en]gine ( http://www.indiedb.com/engines/dragengine
, http://dragengine.rptd.ch/wiki )
- Sowie verschiedene Blender Export-Skripts und Game-Tools

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