Alt + tab freezes screen

[Subodh-Bny]

Using alt tab sometimes freezes the whole screen and there is no way to solve it unless you force restart the PC

[eexpress]

Same here.

[czareq089]

Same here, in my case the only other option rather than force restarting is force closing all programs (ALT + F4)

[Subodh-Bny]

Same here, in my case the only other option rather than force restarting is force closing all programs (ALT + F4)

i just stopped using the extension

[blueoc-phucpham]

I got this bug too

[JE-Amouel]

I had the same problem under gnome 45, but it turns out that it was due to a conflict with another extension which also triggered when I did alt+tab,

Do you think this could also be the case for you?

[dsheeler]

Sorry for my silence on this issue. I have never had a freeze myself. It probably is not a bug in the extension, but likely as @JE-Amouel suggests caused with a conflict with another extension.

Can anyone with this issue send steps to reproduce?

[czareq089]

For me personally, I can no longer reproduce this issue so it seems kind of weird. Anyway here are the extensions that I use and these are not the cause of conflict.

[JE-Amouel]

For me the conflict occurs with aatws which is also an alt+tab switch, and which also provides a dock mode which I find much more productive, so I do not use the alt+tab with this extension, and i prefer to use alt+tab with coverflow.

On version 42.9 of GNOME, the two extensions do not conflict, coverflow overwrite the alt+tab behavior of aatw, so I can use coverflow with alt+tab and at the same time , aatws with is dock mode.
But on GNOME versions 45+, when I install aatws and coverflow the two conflict;
reason why I made this feature request #239

so the steps to reproduce on my side are:

• install aatws
• install coverflow
• press alt+tab

[pyhofficial]

Same here

[nutuxedo]

got this bug too, had to uninstall the extension till this gets fixed

[Sputnik2a]

On my system the freeze is nondeterministic. But it occurred with ALT-TAB as well as SUPER-TAB. If I wait after such freeze up to the system goes to sleep, the desktop is fully responsible again after waking up system.

I have activated the logging of the extension and found a NULL pointer access violation by the extension. If the extension freeze, it died every time with the same exception (log is in reverse order):

Aug 31 14:57:11 gnome-shell[2337]: JS ERROR: TypeError: this._settings is null
	lightenBackground@file:///home/user/.local/share/gnome-shell/extensions/CoverflowAltTab@palatis.blogspot.com/platform.js:601:13
	animateClosed@file:///home/user/.local/share/gnome-shell/extensions/CoverflowAltTab@palatis.blogspot.com/switcher.js:962:63
	activateSelected@file:///home/user/.local/share/gnome-shell/extensions/CoverflowAltTab@palatis.blogspot.com/switcher.js:845:14
	_keyReleaseEvent@file:///home/user/.local/share/gnome-shell/extensions/CoverflowAltTab@palatis.blogspot.com/switcher.js:789:22
	@resource:///org/gnome/shell/ui/init.js:21:20
Aug 31 14:57:10 gnome-shell[2337]: Ignoring length property that isn't a number at line 2461, col 24
Aug 31 14:57:10 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ] Creating Switcher DONE
Aug 31 14:57:10 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ]     Creating Sub-switchers DONE
Aug 31 14:57:10 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ]     Creating Sub-switchers
Aug 31 14:57:10 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ] Creating Switcher
...
Aug 31 12:47:06 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ] DBus Name Acquired: org.gnome.Shell.Extensions.Coverflowalttab
Aug 31 12:47:06 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ] DBus Bus Acquired: org.gnome.Shell.Extensions.Coverflowalttab
Aug 31 12:47:06 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ] Enabling DONE
Aug 31 12:47:06 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ]     Creating New Manager DONE
Aug 31 12:47:06 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ]     Creating New Manager
Aug 31 12:47:06 gnome-shell[2337]: [CoverflowAltTab@palatis.blogspot.com][LOG  ] Enabling

Hopefully, it can help you a little bit to find the bug.
Used Version: CoverflowAltTab v75 under Arch Linux with gnome-shell 46.4.

[dsheeler]

@Sputnik2a Thank you for the logs!!! That's the best clue I have so far on this issue.

[dsheeler]

It's a strange issue, but I can try a fix that might stop the crash without me understanding the reason it's happening, which is unsatisfying, but better than crashes.

[dsheeler]

@Sputnik2a and all, I have committed something to the main branch that might fix this issue. Can anyone try it out?

[dsheeler]

Hi All, I think with version 76, I have fixed the freezes. I understand why they were happening, too! Let me know if you try it and it fixes things for you please!

[dsheeler]

@Sputnik2a special thanks for those logs. They were the clue that I needed!

[Sputnik2a]

@dsheeler You're welcome.

I had patched your commit 940b2a9 into my local v75 installation and tested it the last days. No freeze 😎 nor any side effect. Now, I test it with v76. Thanks for your great work.