Workspaces - Workspace Switcher renders incorrectly on multi-monitor setup with different resolutions

[Stewart Wilson]

When I launch the Workspace Switcher with a second monitor attached to my laptop, set to a different resolution than the laptop display, the rendering is corrupted and window hit testing is broken.

Setup:
Laptop: Acer Aspire Timeline X 4830T: Intel Graphics 3000
Second Display: VGA monitor

Display does not seem to be blanking in-between painting frames whilst animating to the final Workspace Switcher view.
Hit-testing for windows is broken.
See attached screenshot of Workspace Switcher shown with resolutions 1366x768 (laptop) and 1440x900 (monitor).

In the short term, the rendering and hit-test issues need to be fixed.

Beyond that, the arrangement of workspaces in the switcher need to be updated to match the new design in the multi-monitor spec:
https://docs.google.com/a/canonical.com/document/d/1aHvJ-iIw-59bXTYBmIhQqEx0za2h9jpFE_RhZ2VOvJc/edit?hl=en_US#bookmark=id.8un55uehv7bj

[Tim Penhey (thumper)]

Stewart, should I know what window hit testing is?

Also, works for me... Can you try again?

[Stewart Wilson (stewartw)]

Hi Tim,
Sorry, by window hit testing I mean identifying the window under the mouse cursor when starting a drag. As of Precise (dev branch) + Unity 5.2.0 this is working correctly now.
However, the rendering is still not correct: the background is now being blanked for each frame of the transition animation, but the workspaces on the second display are not positioned correctly. See image attached for 2 displays: 1366x768 and 1440x900.

[greg (grigorig)]

Please see #949502. The culprit is the "expo" plugin in the compiz main plugins. I looked around the code, but it's very messy. Expo has various modes, and they're all mixed together and in spaghetti fashion. It's not easy to determine how positioning and scaling is supposed to work. I'll take another look at it if I got the time.

[Tim Penhey (thumper)]

Stewart,

Please don't add "extra work" to bug reports, like extending to meet specs. We should have explicit bugs for that (if bugs are needed).

Also, has the latest compiz fixed the visual rendering?

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Andrea Azzarone (azzar1)]

Thank you for taking the time to report this bug. We have tried to recreate this on the latest release of Ubuntu and cannot reproduce it. This bug is being marked as Invalid. If you believe the problem to still exist in the latest version of Ubuntu please comment on why that is the case and change the bug status to NEW.