Ctrl+U (Key command only) causes a system freeze on Ubuntu 17.10 with default (Wayland) window manager.

• Dec 15, 2017 - 10:08

I think I may have found a critical bug, but could someone please confirm before I enter it in the issue tracker?

OS: Ubuntu 17.10
MuseScore version: 2.1. (installed from repository).

Steps to reproduce:

  1. Launch MuseScore
  2. Press key command Ctrl+U (fullscreen).
  3. The entire system freezes. I had to use a SysRq method to recover from this (either Alt+SysRq+K or Alt+SysRq+REISUB), in order to avoid a hard reboot.

Note: Clicking on Menu->View->Fullscreen works fine, this issue happens ONLY when using the key command Ctrl+U.


No freeze with OpenSuse Leap and XFCE.
Maybe you could check if it occurs with different window managers too, to exclude that's not only a behavior with a specific window manager/desktop system.

In reply to by kuwitt

Good call, kuwitt! Thanks for the suggestion. I just tried switching from the (new) default window manager on Ubuntu 17.10 (Wayland) back to Xorg and indeed this issue doesn't occur in Xorg.

Seems this only happens with Wayland, then. Could someone running Wayland also give it a try, just in case?

edit: (I've edited the subject of this thread to hopefully make the issue clearer)

You could also check if it happens after defining another shortcut for full screen (to check if there's a conflict with the shortcuts of your desktop system)

So, does this point to a bug in the Wayland window manager, or a bug in MuseScore?

Should I put this in the issue tracker or not?

In reply to by Xasman

Without being a development contributor and without having installed Wayland on my system, my 2 cents:

Maybe it could be useful to check, if it also occurs with the nightlies of 2.2 and 3.0.
And a further useful investigation I could imagine: to check, if you've a similar behaviour with other (Qt)-applications and Wayland.

In reply to by kuwitt

OK, I just ran a few tests:

In Wayland:
MuseScore 2.2 nightly (2017-12-17): Using Ctrl+U to go fullscreen does not work but also does NOT cause the system freeze (unlike in MuseScore 2.1). The main GNOME menu top bar disappears momentarily but then reappears and nothing else happens.
However, going to fullscreen using the menu command does work normally, but using Ctrl+U to toggle back FROM fullscreen to normal DOES still cause the system to freeze (as per MuseScore 2.1 in Wayland).

The only other qt application I have installed (AFAIK) is Virtual Box. Using Key commands (HOST+F) to toggle between normal and fullscreen in Virtual Box works normally.

In Xorg:
Both MuseScore 2.1 and 2.2 work normally.

Virtual Box also works normally.

P.S. I couldn't find a download link for MuseScore 3.0 so couldn't test that.

In reply to by Jojo-Schmitz

Hmm..thanks. How very unintuitive.

Anyway, I've now tested all three versions (2.1, 2.2 and 3.0).

In fact, they all seem to behave similarly now in this respect; i.e., somewhat inconsistently.

Firstly, in all MS versions, the Ctrl+U key command is only problematic in Wayland. In Xorg it's fine.

Secondly, in all three MS versions, replication of the issue is a little inconsistent; sometimes the first press of Ctrl+U freezes the system but sometimes it doesn't freeze until the second or sometimes even third press. However, this key command DOES reliably produce a system freeze after no more than three presses of the key command. I did wonder whether the behaviour would be different whether or not the MS window was maximised, so I tested both states in all three versions, but that seems to make no tangible difference.

Hope that's useful. So, is it a Musescore or Wayland bug?

In reply to by Xasman

I'm not sure (but as mentioned without being a developer). But when I enter the phrases "Wayland" and "freeze" in a search engine I get some other "freeze results". Maybe you could also report it in the Wayland bug tracking system (?).

(I can't check it because Wayland isn't supported in OpenSuse Leap.)

Do you still have an unanswered question? Please log in first to post your question.