Compiz ‘Thumbnail Window Previews’ artefacts (further fix +)

The solution proposed by David Black won't eliminate all artefacts related to the thumbnail window previews. To see this, apply the proposed solution and then just type "wish" in a MATE-Terminal. The resulting window has a geometry of 200x200, and the corresponding thumbnail still gives rise to the reported artefact. Same problem with any other top-level window having a sufficiently small size.

Alternative solution: Change org.compiz.profiles.mate.plugins.thumbnail.border from the value 12 to 19 (or higher).

With this patch, I could no longer reproduce that annoying thumbnail artefact, regardless of whether the change proposed by David Black was in effect or not.

BTW: IMHO, the shadow effect generated by the original offset value of 6 (for active-shadow-x-offset, active-shadow-y-offset, inactive-shadow-x-offset and inactive-shadow-y-offset) looks better than the one corresponding to the proposed offset value of 2). Of course, this is just matter of taste.

After some more testing I came to the conclusion that proportionally balanced shadows (as proposed by David Black) will result in improved appearance when using a light theme (and will be OK for dark themes, too). Also, with that fix in effect, it is sufficient to change the value of org.compiz.profiles.mate.plugins.thumbnail.border from 12 to 15 (instead of 19) in order to completely eliminate the reported artefact. Consequently:

Alternative solution revisited: Apply the fix proposed by David Black AND change the value of org.compiz.profiles.mate.plugins.thumbnail.border from 12 to 15.

This bug was fixed in the package compiz - 1:0.9.13.1+17.10.20170515-0ubuntu1

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compiz (1:0.9.13.1+17.10.20170515-0ubuntu1) artful; urgency=medium

  [ Martin Wimpress ]
  * mate: Avoid artefacts of Windows Thumbnail Previews (LP: #1606369)

 -- Marco Trevisan (Treviño) <mail@3v1n0.net> Mon, 15 May 2017 05:51:32 +0000

Hello David, or anyone else affected,

Accepted compiz into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/compiz/1:0.9.12.3+16.04.20171116-0ubuntu1 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 on 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-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. 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!

I'm not sure how to reproduce this bug, how do I get to see the 'thumbnail preview' of an application on MATE?

Works here with

LANG=C apt-cache policy compiz
compiz:
  Installed: 1:0.9.12.3+16.04.20171116-0ubuntu1
  Candidate: 1:0.9.12.3+16.04.20171116-0ubuntu1
  Version table:

This bug was fixed in the package compiz - 1:0.9.12.3+16.04.20171116-0ubuntu1

---------------
compiz (1:0.9.12.3+16.04.20171116-0ubuntu1) xenial; urgency=medium

  [ Eleni Maria Stea ]
  * Added option to disable blend in grid plugin (LP: #1700859)
  * Move: add options for showing only the window shape (filled or not)
    (LP: #1700859)

  [ Alberts Muktupāvels ]
  * Ensure that surfaces used by metacity theme have device scale set to
    1 . (LP: #1530277) (LP: #1530277)
  * Use AnyPropertyType when getting _MOTIF_WM_HINTS property. (LP:
    #1702297)

  [ Martin Wimpress ]
  * mate: Avoid artefacts of Windows Thumbnail Previews (LP: #1606369)

  [ Marco Trevisan (Treviño) ]
  * move: damage all the border area in outline mode and ignore
    transparent colors (LP: #1700859)
  * grid: ignore alpha in colors when not blending, and fix animations
    (LP: #1700859)
  * resize: add support for disabling transparency and avoid over-
    damaging in outline mode (LP: #1700859)
  * Screen: add averageColor to get the current desktop average color
  * unity-lowgfx.ini: remove unsupported unity option

 -- Marco Trevisan (Treviño) <mail@3v1n0.net> Thu, 16 Nov 2017 23:00:54 +0000

The verification of the Stable Release Update for compiz 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.