Using OpenGL as a window manager

[Gian Filippo Pinzari]

Martijn Sipkema wrote:
> I think an application should
> be able to draw to the framebuffer and know what the resulting pixels
> will be.

I think you meant that applications should have the option
to disable any transformation performed by the X server, so
that they can retain complete control of what is displayed
(according to the X protocol). Knowing what the resulting
pixels will be on the framebuffer, anyway, should be exclu-
sive responsibility of the X server. We all should agree on
preserving a layer of separation between the framebuffer and
the X protocol, the way we have separation between HTML and
the CSS.

Sorry if it is completely off-topic here, but IMHO it is
important to stress this. For example, I think that X clients'
developers should be strongly discouraged from making any
kind of assumption on the content of the framebuffer. This
obviously includes querying the X server to get content of
pixmaps and windows, and not only for security considera-
tions.

I vote for modifying the X core protocol specification to
return BadAccess to -any- GetImage, unless explicitly enabled
by the user :-) (I know that X security permits such a
behaviour already, but you can't disable GetImages if there
are apps relying on them). It should be at least forbidden to
query the content of windows, including GetImage on pixmaps
that were target of CopyArea from windows. It would be a
radical solution, but it would make X11 a much better protocol
for running networked applications both efficiently and
securely :-).

/Gian Filippo.