Detecting whether a compositing manager is running

[Havoc Pennington]

On Fri, 2005-09-16 at 09:59 +0200, Christian Neumair wrote:
> It can be useful for applications and desktop environments to detect
> whether an application manager is running, for instance to decide
> whether it should use the rgba visual. According to Matthias Clasen,
> there are no means to detect this as of writing [1]. Maybe we should
> have a per-Screen flag which returns whether a compositing manager is
> running for that particular Screen.
> Opinions?
> 

Having a compositing manager selection makes sense, but choosing a
visual based on whether a CM is running seems very broken to me. 
What if your app starts before the CM, or what if there's no CM at first
and someone runs one later? There's no way to change the visual
retroactively.

I've been asking for a general "are we in snazzy new graphics world, or
old classic X graphics world" flag but I think it roughly speaking needs
to be set in the X configuration (ideally dynamically detected) and
would say something like "this server is fast enough to do at least
basic drop shadow type effects and supports RENDER and COMPOSITE"

This would then be set as an X property or something and everything
would key off of it. If we could just have one setting, "do new stuff"
or "stick to old school" that will keep us from having to test every
desktop and app with a huge matrix of detailed settings. We can test
_with_ flashy effects and a CM running, and without, and only those two.

Havoc