headless wayland sessions, wayland apps displayed to apps

[David Jackson]

With Wayland will we be able to:

Have multiple seperate wayland sessions on the same computer, as many as
one wishes, with many of them being headless, accessible if the user wishes
through a remote desktop solution such as VNC? Will be able to use a
command line switch or environment variable to determine which wayland
session an application should be started in on a per application basis?

Does the wayland environment provide information on what areas of the
screen are visible to apps, similar to Expose events? This could also be
done with a pointer to shared memory data structure that contains a list of
exposed areas. If this is not provided, I would be concerned applications
will waste time drawing areas of their window that are not visible.

I previously asked if one can run an rootless and an session in-window X
Server as a wayland client, to a wayland session, so x applications can be
displayed on a wayland display, and if one can display a wayland session
and even individual wayland apps onto an X server. I think that these are
very important features.

Being able to display  individual wayland apps to an X server selectable at
runtime, is a highly desirable feature, this would solve the need for
headless remote desktop sessions, since I could display wayland apps to
Xvfb (headless) and use x11vnc with Xvfb.

These features will be necessary. The fact is, toolkits and applications
cannot be trusted to provide runtime switchable display targets between
wayland and X11. We've had experience with similar situations that shows
that application developers will neglect this. Back when XRender extension
was implemented, a large number of X applications ended up not supporting a
fallback for servers that did not support XRender, despite the assurances
that they would. This led to X applications not working at all on servers
that did not support X render. The situation will be similar this time
around. A number of applications will neglect support for display to x11.

Users should not be forced to give up their x11 environment, many of us
have specially tuned X window manager configurations,  and the way to
assure that this will not happen is to gaurantee that individual wayland
only applications can be displayed to an X server through some facility for
this purpose, allowing us to run wayland applications inside our X sessions
with our preferred X window manager.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/wayland-devel/attachments/20121203/18ea85dd/attachment.html>