ALT key crashes system GUI with some layouts

[Matt Mayfield]

This is the first bug I've filed in Launchpad; please let me know if there is a way to categorize these or if I'm committing any kind of faux pas. Thank you!

Steps to reproduce:
- Install Ubuntu MATE 18.04 daily build dated 2017-11-23
- Open MATE Tweak
- Choose Mutiny or Cupertino panel layout
- Open any application with menus (Caja, LibreOffice, etc.)
- Press Alt key

Expected behavior:
- HUD opens, and/or menu accelerators become underlined

Actual behavior:
- LightDM and/or X11 crashes (freezes, unresponsive)
- Must switch to another terminal and `sudo killall lightdm` to recover

Other info:
- Running in VirtualBox 5.1.20 r112629 on Mac OS X host
- Installed to virtual hard disk, not running off live ISO image

[Matt Mayfield (mdmayfield)]

This does not seem to occur in layouts that do not use the Global Menu. (i.e. Redmond, Traditional, etc.)

[Etienne Papegnies (etienne-papegnies)]

Hello
Thank you for this report.
Can you please provide some more information about the setup?

- Hardware of Host machine
- Memory allocated to the VM
- Number of CPUs allocated to the VM

Also what are your window manager settings in MATE Tweak?

[Matt Mayfield (mdmayfield)]

Sure:

- Host hardware: Intel i7 8-core, 16 GB RAM, AMD Radeon R9 270X
- VM guest has 4GB RAM and 4 CPU cores.

I had been using Compiz but also saw this behavior with No Compositor. After some further testing, I got the HUD / menus to work OK with the compositor set to Marco Software Compositor.

There were other general instability issues that are hard to pin down while changing window compositors (Global Application Menu stops working entirely; windows become undecorated; many other small confusing things hard to describe). This is making it tricky to focus on the single issue of the freeze.

I did not see anything in the lightdm or Xorg logs that seemed related, or anything around the times I reproduced the issue.

My next step is to take a snapshot of the VM in its current state, then update using apt to see if anything has changed.

[Matt Mayfield (mdmayfield)]

Typing up notes as I do more tests.

OK, I can confirm that the hang/freeze still happens with latest updates as of 2017-11-28 15:56 UTC, using window manager Marco (Compton GPU compositor).

Upon switching to Marco No Compositor and logging then and logging in, the global menus disappeared from the top panel. After a full restart of the VM, the menus reappeared.

The hang/freeze also happens with marco-no-compositor.

Ctrl-alt-F1, log in, sudo killall lightdm, go back to X and the GUI is already frozen and I see two Network indicators on the top right instead of one. Hard-reset the VM. Open MATE Tweak, switch window manager to Marco (Software compositor).

Try Alt key, X freezes/hangs. Ctrl-alt-F1, sudo shutdown -r now. VM restarts, test Alt key again, freeze/hang --- *even though in a previous test the software compositor worked OK*.

This is a difficult issue to pin down because it is very inconsistent.

Are there any log settings I can enable that may help provide more insight?

[Matt Mayfield (mdmayfield)]

Trying a couple other things. All of these with Marco (Software compositor).

- With the VM set to 1 single CPU core: issue persists.
- VM's GPU RAM changed from 128MB to 32MB: issue persists.
- Turned off 3D acceleration for this VM: issue persists.

[Matt Mayfield (mdmayfield)]

I have reproduced this bug on actual hardware (Dell XPS 15 9550) using a live USB of today's 18.04 daily ISO (2017-12-28). One sequence of events that reproduced the issue was:

1) Boot from USB (UEFI boot in this case)
2) Close Welcome application
3) Open MATE Tweak
4) Choose Cupertino panel layout
5) Choose Compiz compositor (this may or may not be necessary)
6) Open Caja, press Alt a few times to bring up the HUD
7) Open Terminal using CTRL-ALT-T shortcut
8) ----- Notice in upper right, extra "EN" keyboard layout icon next to keyboard indicator
9) Press Alt
10) X session freezes and becomes unresponsive

At this point the only way I've found to regain control is to switch to another TTY and sudo killall lightdm.

[Matt Mayfield (mdmayfield)]

I've recently discovered that by using Ctrl-Alt-F1 and issuing `sudo killall mate-hud` I can regain control of the session. Perhaps the MATE HUD is where the issue lies?

[Martin Wimpress  (flexiondotorg)]

Here is the upstream bug report:

  * https://github.com/ubuntu-mate/mate-hud/issues/16

[Launchpad Janitor (janitor)]

This bug was fixed in the package mate-hud - 18.04.5-0ubuntu1

---------------
mate-hud (18.04.5-0ubuntu1) bionic; urgency=medium

  * New upstream release. (LP: #1734271)

 -- Martin Wimpress <email address hidden> Thu, 15 Feb 2018 15:18:04 +0000