[Bug 71030] Re: Lock Screen blanks screen instead of showing screensaver (on external monitor)

[Bryce Harrington]

Here's a workaround:

I restarted X, then killed gnome-screensaver.  At this point I could
start gnome-screensaver-preferences, and so switched from 'Random'
screensaver to 'Blank Screen'.  From this point, ctrl-alt-l started the
screensaver, and it worked on all three monitors, and went to the unlock
dialog properly on activity. Looking through the various screensaver
options, it appears a handful of the screensavers work (apparently the
non-3D ones?)

I did see the following error messages when the screensaver activated,
but haven't seen any other misbehavior otherwise:

(/usr/lib/gnome-screensaver/gnome-screensaver-gl-helper:9778): Gdk-
CRITICAL **: gdk_x11_visual_get_xvisual: assertion `visual != NULL'
failed

(/usr/lib/gnome-screensaver/gnome-screensaver-gl-helper:9779): Gdk-
CRITICAL **: gdk_x11_visual_get_xvisual: assertion `visual != NULL'
failed

(/usr/lib/gnome-screensaver/gnome-screensaver-gl-helper:9780): Gdk-
CRITICAL **: gdk_x11_visual_get_xvisual: assertion `visual != NULL'
failed

A few thoughts on fixes for this bug...

1.  Add a new Random2D screensaver theme which activates only the non-3D 
screensavers.  
2.  Or add a mechanism to detect if the user's X config can actually run the 
3D screensavers and only enable them if the prerequisites are met.
3.  Since gnome-screensaver-preferences was crashing, I couldn't turn off
the screensaver that was causing the problem.  Perhaps include a checkbox
for being able to see previews of the screensaver, that's off initially by default
or something.

-- 
Lock Screen blanks screen instead of showing screensaver (on external monitor)
https://launchpad.net/bugs/71030