Re: Fixing the flicker problem when toplevel windows pop up over a running screensaver

["Ray Strode" <halfline gmail com>]

And, of course, I mixed two of Bryan's email addresses into one when
sending the mail, so it bounced...  Resending so he gets it.  It would
be better if replies went to this message instead of the first one.

On 7/23/07, Ray Strode <halfline gmail com> wrote:
> Hi guys,
>
> So while at GUADEC, Alex Larsson and Bryan Clark asked me about the
> feasibility of setting up GDM to autologin a user at boot up and then
> immediately lock the screen.
>
> The idea is that someone owns a laptop that only that person users,
> they go to boot it up in the morning and while its booting go to get
> coffee or something.  When they come back it would be neat if the
> session was already loaded and just needed to be unlocked.
>
> Anyway, I briefly looked into the idea and came up with one bit of
> unpleasantness.  As everything loads..the gnome-session splash screen,
> nautilus, the panel, etc, there is a lot of flicker as each window is
> raised and then the screensaver window is re-raised.
>
> There are two ways to fix this I think:
>
> 1) Use the composite overlay window
> 2) Use the MIT x screensaver extension
>
> Both provide an overlay window that is always on top.  Note, the first
> one won't work if the user is running a compositing manager because
> the compositing manager will already be using the window for it's own
> drawing.
>
> I don't remember all the problems with the screensaver extension that
> has prevented its use in gnome-screensaver before, but I kind of
> vaguely remember two issues:
>
> 1) No way to do fade in
> 2) No way to run different screensavers on different monitors
>
> I played around a bit during the last couple of days of GUADEC and
> wrote a lame little test app that comes up with solutions for those
> two problems.  You can get it with
>
> git clone git://anongit.freedesktop.org/~halfline/test-screensaver-extension/
>
> It solves the first problem by making the screensaver window have a
> None background pixmap so that when the screensaver window gets mapped
> the contents that were on screen stay on screen.  It does mean you
> won't see windows update during the fade in, but that could be fixed
> if a compositing manager is running by giving the window an alpha
> value I think (although I didn't try yet).
>
> It solves the second problem by not actually using the screensaver
> window, but instead creating child windows on the screensaver window.
>
> Note, the test app isn't anything but an example program to show that
> those two problems are fixable.  The app doesn't do a real-time fade
> animation (it just paints progressively darker in a loop basically),
> it doesn't show anything interesting while active, etc.
>
> Jon, can you think of other problems that made the screensaver
> extension infeasible?  I sort of vaguely remember Keith saying the
> screensaver extension was supposed to break grabs, but that ended up
> being unimplemented.  Was there some impedance mismatch between its
> concept of idle and gnome-screensaver's concept of idle?
>
> --Ray