Re: Screen saver support patches

[Brian Cameron <Brian Cameron Sun COM>]

Laurent:

> I'd like to use GDM to start a screen saver-like program.
> This would allow the machine to join a distributed computing
> system when the machine is idle.
>
> Currently in GDM one can specify a program using
> greeter/BackgroundProgram. There are two shortcomings, however:
>
> - The program is run immediately after GDM is started.
>
> - The program is not restarted after a while when it has exited.
>
> I patched gdmlogin to implement the following features:
>
> - You can specify greeter/BackgroundProgramInitialDelay
>   which controls when the program is run after GDM is started.
>  
> - You can specify greeter/BackgroundProgramNextDelay
>   which controls when the program is restarted after it has
>   exited.
>  
> Essentially, I use a timeout to start the program when it is
> time, and a watcher to detect when the program has exited.
> I replaced calls to gdm_run_command(), run_backgrounds(), and
> gdm_kill_thingies() with their equivalents in the new API.
> The logic of the program did not change much.

The above seems reasonable.

> I'm sending diffs against version 2.6.0.8 of gdm. The
> integration is not complete. In particular,
>
> - Need to remove backgroundpid, gdm_run_command(),
>   run_backgrounds() and gdm_kill_thingies() (commented out).

Please clean up your patches.  Also submit a bug under category
gdm in http://bugzilla.gnome.org and attach your patch there.
Why is it necessary to remove gdm_kill_thingies()

> - Must no longer ignore SIGCHLD (commented out).

Why is this necessary?

> - Maybe let user specify -1 to disallow restarting?

No, there should be an extra configuration option to turn this
feature on/off.  Much like TimedLoginEnable.

> - Documentation for the user.
>
> The patched version works almost correctly on my system, but
> there is still one problem. While the program always get
> mouse focus, it does not always receive keyboard focus.
> Sometimes you can login while the screen saver is running
> (the screen saver gets killed, but it should go when the
> user is typing).

This problem will need to be corrected before we should apply
the patch, I think.  I'm not sure how to fix this, but perhaps
someone else might have a comment.  You might take a look at
the gdmwm.c file.  GDM uses a light window manager.  It might
be necessary to add some code to tell the window manager to
deal with focus issues.  Perhaps something like
gdm_wm_focus_window is what you need?

Also, you didn't update docs/C/gdm.xml with information about the
new feature, which is necessary before a patch would be accepted.
The documentation should highlight that this is a feature for
the GTK+ Greeter.

Brian