** Summary changed:

- gnome-display-properties locks up X when changing multi-head layout
+ gnome-display-properties blanks X when changing multi-head layout

** Description changed:

  Binary package hint: gnome-control-center
  
  Problem:  When swapping dual monitors left to right, on apply in gnome-
  display-properties one screen (the left one) blanks out; repeating this
  swapping a couple times locks up Xorg.  Using the 'xrandr' command line
  tool to do the same operation works perfectly with no lockup.
  
  Discussion:  I have a dual-monitor setup using xrandr on an ATI 5xx card
  using the -ati driver.  I tested out gnome-display-properties by
  launching it and then simply swapping my two monitors left-for-right (no
  other changes).
  
  The first time I hit apply, the left monitor turned blank with "No
  Signal" shown.  The right monitor displayed what was on the left monitor
  before, and did so in a manner that suggested gnome-panel was still
  assuming two monitors and not one.  The cursor also disappeared off the
  edge of the remaining screen in a manner suggesting that X thought there
  was another monitor.  In the past, vt-switching would sometimes bring
  the second screen back, but this time it didn't.  I let the confirmation
  dialog time out, and it returned the system to the original layout.
  
- Repeating this exact process again, this time X locked up.
+ Repeating this exact process a few times, both screens blank.  I can
+ restore them by vt switching and/or re-running xrandr.
  
  I attempted to reproduce the issue using only xrandr, via the command
  `xrandr --output DVI-0 --left-of DVI-1`, alternating --left-of and
  --right-of appropriately.  I repeated this a dozen times and it always
  worked perfectly.
  
  (In fact, with gnome-display-properties, there is always a couple second
  delay after hitting apply, whereas with the xrandr command line tool,
  the change is instantaneous.  Maybe that's a clue.)
  
  Because I can reproduce this bug only when using gnome-display-
  properties, and not with 'xrandr', I am assuming this to be due to a bug
  in the gnome capplet, not a bug in Xorg.

-- 
gnome-display-properties blanks X when changing multi-head layout
https://bugs.launchpad.net/bugs/351900
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