Unity panels steal input events while under (some) fullscreen windows

[Michael Matthews]

I have 3x 1920x1080 monitors arranged horizontally. Unity is configured to duplicate the launcher on every monitor.

Video cards:

2x AMD R270 in CrossfireX
Driver: fglrx-updates (because the open source driver would always kill my X session when I open any LibreOffice app)

Description:

When telling an application to go full screen, it is correctly displayed full screen; however, when clicking in that full screen window, the Unity panels (hidden underneath) will steal its input events.

Problems with:

 - Chromium playing any YouTube video full screen
 - VMware Player in full screen mode

No problem with:

 - Chromium browsing any website while in full screen browsing mode (e.g. pressing F11)
 - Chromium playing any YouTube video full screen *after* pressing F11 to put browser in full screen mode
 - Default movie player playing video in full screen mode

As a layman, it appears there are multiple methods for an application to go full screen, and at least one of those methods is not handled properly by either Unity or something related to the window manager.

[Michael Matthews (michael-a-matthews)]

Machine specs:

Ubuntu 15.04 (amd64)
AMD 8350 Black Edition
16 GB DDR3 ECC
1 TB drive with Windows 7 x64 / Ubuntu 15.04 (amd64) in dual-boot (grub)
2x Radeon 270 in CrossfireX
3x 1920x1080 monitors attached to primary Radeon 270

[Michael Matthews (michael-a-matthews)]

Update:

This only happens when this option:

System Settings -> Displays -> Launcher placement == All displays

If I set the launcher to only appear on a specific display, the launcher (and menu bar) no longer steal input from any full screen windows. This problem seems like a bug in Unity. I haven't tested it with a different video driver.

[Marco Trevisan (Treviño) (3v1n0)]

Thanks for the report, I'm trying to figure Mh, so... I don't get this issue (but I only have two monitors here).

Can you give me the output for
  xprop -root

?

[Michael Matthews (michael-a-matthews)]

I'd like to add that my comment (#2) is not correct. The bug went away for a while when I set the launcher to only show up on one display, but the bug later began happening regardless of the option. It's intermittent. Sometimes a program will go full screen correctly; other times the Unity panels will steal the "full screen" program's input.

[Marco Trevisan (Treviño) (3v1n0)]

Mh, I've been able to reproduce this problem as well... But it only happens when the fullscreen window is not focused. Can you confirm?

[Michael Matthews (michael-a-matthews)]

Yes, I can confirm that.

It also explains why some applications appear to be affected while others are not.

[Marco Trevisan (Treviño) (3v1n0)]

Mh, this makes things harder to fix... The fact is that the shell is not drawn when there are some fullscreen windows around, and that's fine... But compiz adds it back on top when a fullscreen window has no focus.

This means that to fix the issue we can both show the shell on top of these windows (not sure the best option), or make the shell not to take input in this scenario... And both of these cases are quite tricky to handle (especially the former).

[Michael Matthews (michael-a-matthews)]

>> But compiz adds it back on top when a fullscreen window has no focus.

I'm guessing the problem is that Unity's panel window(s) are not created in a way that allows compiz to keep them hidden (under full screen windows) independently for each display.