/usr/bin/compiz:11:ScaleScreen::getWindows:unity::UnityScreen::OnInitiateSpread:sigc::internal::signal_emit0:sigc::signal0:unity::PluginAdapter::NotifyCompizEvent

[errors.ubuntu.com bug bridge]

The Ubuntu Error Tracker has been receiving reports about a problem regarding unity. This problem was most recently seen with version 1:0.9.12.2+16.04.20160714-0ubuntu1, the problem page at https://errors.ubuntu.com/problem/07d63967ac9e4ad7a1f17990b115a433ed66408c contains more details.

[Impact]

Sometimes gsettings org.compiz.core:/org/compiz/profiles/unity/plugins/core/ active-plugins is not including scale, we need to ensure it's always there when loading unity session.

[Test case]

There's no easy way to reproduce the issue without some manual intervention.
So one way is, set the unity active plugin list without scale:
  gsettings set org.compiz.core:/org/compiz/profiles/unity/plugins/core/ \
    active-plugins "['core', 'composite', 'opengl', 'compiztoolbox', 'vpswitch', \
    'snap', 'mousepoll', 'resize', 'place', 'move', 'wall', 'grid', 'regex', \
    'imgpng', 'session', 'gnomecompat', 'animation', 'fade', \
    'unitymtgrabhandles', 'workarounds', 'expo', 'ezoom', 'unityshell']"

When restarting your session, the scale plugin should be there again (and thus doing Super+W should work, and so spreading multiple windows of an application).

Also scale plugin should be correctly reloaded and listed in
  gsettings get org.compiz.core:/org/compiz/profiles/unity/plugins/core/

Another way to reproduce is:
 1. Open two windows of the same application
 2. Launch the command above
 3. Click on launcher icon to trigger the application spread

Unity should crash and immediately being reloaded. Now pressing the launcher icon should properly start the spread.

[Regression Potential]

Compiz load time might be increased, custom plugin list could be reverted to the default ones.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity - 7.5.0+16.10.20160727-0ubuntu1

---------------
unity (7.5.0+16.10.20160727-0ubuntu1) yakkety; urgency=medium

  [ Andrea Azzarone ]
  * [LockSceen] Remove numlock warning. (LP: #1526322)
  * Make sure initiate and terminate callbacks are not empty before
    calling them. (LP: #1605012)
  * Properly destroy close_button_ to properly disconnect lambda. (LP:
    #1605010)
  * Use the standard notification-device-eject in the "device eject"
    notification. This allows us to scale it properly on high-dpi
    setups. (LP: #1605231)
  * Add tools to enforce unityshell plugin for the current profile and
    add "move" and "resize" plugins as requirements. (LP: #1506023,
    #1605007)
  * When locked discard damages from windows below lockscreen. (LP:
    #1605180)

  [ Eleni Maria Stea ]
  * DecoratedWindow: Added shadows for shaped windows

  [ Marco Trevisan (Treviño) ]
  * LockScreenAcceleratorController: ensure callbacks are valid before
    calling them (LP: #1605012)
  * DecoratedWindow: Cleanup shadows for shaped windows, reduce
    recomputation

 -- Marco Trevisan (Treviño) <[e-mail]> Wed, 27 Jul 2016 10:25:54 +0000

[Chris J Arges (arges)]

Hello errors.ubuntu.com, or anyone else affected,

Accepted unity into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unity/7.4.0+16.04.20160801.2-0ubuntu1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity - 7.4.0+16.04.20160801.2-0ubuntu1

---------------
unity (7.4.0+16.04.20160801.2-0ubuntu1) xenial; urgency=medium

  [ Andrea Azzarone ]
  * FileManagerLauncherIcon: Don't trust the Quirk::VISIBLE in the ctor.
    (LP: #1599133)
  * [TrashLauncherIcon] Create GFileMonitor in an idle to avoid blocking
    calls. (LP: #1602720)
  * [LockSceen] Remove numlock warning. (LP: #1526322)
  * Make sure initiate and terminate callbacks are not empty before
    calling them. (LP: #1605012)
  * Properly destroy close_button_ to properly disconnect lambda. (LP:
    #1605010)
  * Use the standard notification-device-eject in the "device eject"
    notification. This allows us to scale it properly on high-dpi
    setups. (LP: #1605231)
  * Add tools to enforce unityshell plugin for the current profile and
    add "move" and "resize" plugins as requirements. (LP: #1506023, LP:
    #1605007, LP: #1604657)

  [ Marco Trevisan (Treviño) ]
  * Unity script: use result from unity_support_test to check the right
    COMPIZ_CONFIG_PROFILE to use (LP: #1602377)
  * LockScreenAcceleratorController: ensure callbacks are valid before
    calling them (LP: #1605012)

  [ Eleni Maria Stea ]
  * DecoratedWindow: Added shadows for shaped windows (LP: 1608418)

  [ Marco Trevisan (Treviño) ]
  * DecoratedWindow: Cleanup shadows for shaped windows, reduce
    recomputation (LP: #1608418)
  * UnityWindowView: don't try to deference close_button_ if its' null

 -- Marco Trevisan (Treviño) <[e-mail]> Mon, 01 Aug 2016 13:10:28 +0000

[Chris J Arges (arges)]

The verification of the Stable Release Update for unity has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.