Dual head suspend problem on Precise

[Colin Law]

On 13 March 2012 17:14, Colin Law <clanlaw at googlemail.com> wrote:
> Is anyone else using 12.04 alpha running into this bug [1], "After
> suspend / resume only one monitor of dual head usable"?  I have a
> Toshiba laptop (intel graphics) with an external monitor and after
> suspend/resume it often is only able to use the external monitor.  It
> runs on the external monitor as if it were the only one.  Even
> logout/in does not sort it and I have to reboot to recover.  Using
> System Settings > Displays the laptop monitor shows Off, but setting
> it On does not actually make it come on.  It worked ok on 11.10.
>
> Unplugging the external monitor switches to normal laptop screen, but
> plugging in the external monitor again just goes back to that one
> again.
>
> [1] https://bugs.launchpad.net/ubuntu/+source/pm-utils/+bug/940350

An update just in case anybody is remotely interested.  I have
determined the trigger that causes the problem.
In System Settings > Power I have Do Nothing as the action on lid
close (as there is a problem with this Toshiba Satellite laptop if the
lid is used to suspend). I am suspending using the top panel menu
action.
If I close the lid then I find that it turns off the laptop display
and the PC switches to single monitor mode on the external monitor,
which is ok. On opening the lid it reverts to dual monitor mode.
The bug described is triggered if I initiate the suspend but then
close the lid before the suspend is complete. On re-opening the lid
the PC resumes but the laptop display does not switch back on.

I have updated the bug and now know that all will be well provided I
wait for suspend to complete before closing the lid, so the problem is
reduced to one of minor irritation.

Colin