VNC'ing into gnome-session-flashback (Metacity) in non-shared desktop mode causes Super+KEY pressed behavior

Bug #1440570 reported by Christopher M. Penalver on 2015-04-05
This bug affects 69 people
Affects Status Importance Assigned to Milestone
metacity (Ubuntu)
Dmitry Shachnev
Marc Deslauriers
Dmitry Shachnev

Bug Description

When VNC'ing into gnome-session-flashback (Metacity) with either tightvncserver or vnc4server configured for non-shared desktop mode, when one opens a terminal for example, and types the "s" key, it acts as if the Super key is also pressed along with it. Hence, this appears to be a gnome-* issue.

[Test Case]
Vivid new install setup for tightvncserver:
sudo apt-get update && sudo apt-get -y dist-upgrade && sudo apt-get -y install xrdp gnome-session-flashback && sudo apt-get -y remove vino && nano .xsession
export XDG_CURRENT_DESKTOP='GNOME-Flashback:Unity'
exec gnome-session --session=gnome-flashback-metacity --disable-acceleration-check

sudo nano /etc/xrdp/xrdp.ini

change to:


Log out, log back in, and RDP in via either Windows Remote Desktop Connection or Remmina.

[Regression Potential]
This patch adds an additional check for modmask. It is already in upstream metacity.

WORKAROUND: Applications > System Tools > System Settings > Keyboard > Shortcuts > Disable all shortcuts containing the Super key.

WORKAROUND: Don't use the .xsession file with tightvncserver, but this then creates a shared desktop experience, instead of ones own, not seen by the user at the local console.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: vnc4server 4.1.1+xorg4.3.0-37.3ubuntu2
ProcVersionSignature: Ubuntu 3.19.0-12.12-generic 3.19.3
Uname: Linux 3.19.0-12-generic x86_64
ApportVersion: 2.17-0ubuntu1
Architecture: amd64
CurrentDesktop: GNOME-Flashback:Unity
Date: Sun Apr 5 13:10:40 2015
InstallationDate: Installed on 2014-12-14 (112 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20141213)
SourcePackage: vnc4
UpgradeStatus: No upgrade log present (probably fresh install)

description: updated
affects: vnc4 (Ubuntu) → gnome-flashback (Ubuntu)
summary: - Typing causes Super+KEY pressed behavior
+ VNC'ing into gnome-session-flashback (Metacity) in non-shared desktop
+ mode causes Super+KEY pressed behavior
description: updated
description: updated
description: updated

Dmitry: can you add small patch to metacity? it will make sure that keys without modifiers are not grabbed.

affects: gnome-flashback (Ubuntu) → metacity (Ubuntu)
Changed in metacity (Ubuntu):
assignee: nobody → Dmitry Shachnev (mitya57)
status: Triaged → In Progress
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package metacity - 1:3.14.3-1ubuntu7

metacity (1:3.14.3-1ubuntu7) vivid; urgency=medium

  * Brown paper bag upload.
  * Fix the previous upload to use the function name from metacity 3.14
    (keysym_name, not keysym_to_string).
 -- Dmitry Shachnev <email address hidden> Thu, 09 Apr 2015 14:50:18 +0300

Changed in metacity (Ubuntu):
status: In Progress → Fix Released
tags: added: verification-done
Changed in metacity (Ubuntu Trusty):
status: New → Confirmed
assignee: nobody → Marc Deslauriers (mdeslaur)
Changed in metacity (Ubuntu Utopic):
status: New → Confirmed
Changed in metacity (Ubuntu Trusty):
status: Confirmed → In Progress

Hello Christopher, or anyone else affected,

Accepted metacity into trusty-proposed. The package will build now and be available at in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at . Thank you in advance!

description: updated
Changed in metacity (Ubuntu Trusty):
status: In Progress → Fix Committed
tags: removed: verification-done
tags: added: verification-needed

This fix looks good to me. Thanks!

Chris Good (chris-good) wrote :

I have tested metacity 1:2.34.13-0ubuntu4.1 and while the s key now works correctly (no longer opens the Applications menu), the Super (Windows) key no longer works. For example, Windows+Tab no longer switches between application windows.

I uninstalled the trusty proposed metacity, libmetacity-private0a + metacity-common, and reinstalled the current 1:2.34.13-0ubuntu4 versions to verify that the Windows key actually did work before the proposed patch.

Some may say that the Super key not working is a much smaller problem than the s key always opening the Applications menu.
I'd be OK with not being able to use the Super key but maybe others would consider this a serious regression.
I'll leave it to others more qualified to decide if this should be flagged as verification-done or verification-failed.

My testing was done using Windows 7 Remote Desktop Connection to connect to a Ubuntu 14.04.2 machine running xrdp.
The Ubuntu machine is a client vm of a VMware vSphere host.

Chris Good: Does application switching "works" only pressing Tab (with 1:2.34.13-0ubuntu4 version, where fix is not added)?

Well fix does what it is supposed to do - prevents binding only keys without modifiers.

For me on ubuntu 14.04 with default configuration Alt+Tab and Super+Tab does same thing. For testing I am using Remmina to connect to ubuntu 14.04.

Without fix:
s - opens menu
Tab - switch between last two applications?

With fix:
s - does not open menu. Super + s is supposed to open, but it does not work.
Tab - no longer switch. Alt+Tab works, Super + Tab does not.

Main problem is this - could not find XKB extension. Because of this metacity fails to get modifier for Super key (and other keys). I would say that vnc simply needs to support xkb. Of course this might be fixed in metacity if it is possible to get modifiers without xkb extension. But I have no time to search for solution.

I will set to verification-done since proposed fix does what it should and is already reported by two testers.

tags: added: verification-done
removed: verification-needed
Chris Good (chris-good) wrote :

Hi Alberts,

Yes, Super+Tab only works before patch is added. It doesn't work after patch is added.
As you said, Alt+Tab is an alternative for Super+Tab.
I've done some more testing of Super key shortcuts using shortcuts from

The only other shortcut that worked in the unpatched metacity in the problem scenario, is Super+Shift+TAB, and Alt+Shift+Tab is an alternative.

As there are alternatives for the 2 Super key shortcuts that worked in the unpatched metacity in the problem scenario, there should be few (or no) objections.

Thanks for your help.

Launchpad Janitor (janitor) wrote :

This bug was fixed in the package metacity - 1:2.34.13-0ubuntu4.1

metacity (1:2.34.13-0ubuntu4.1) trusty; urgency=medium

  * Backport upstream patch to not grab keybindings without modmask
    (LP: #1440570, thanks to Alberts Muktupāvels).
 -- Marc Deslauriers <email address hidden> Sun, 26 Apr 2015 12:21:17 -0400

Changed in metacity (Ubuntu Trusty):
status: Fix Committed → Fix Released

The verification of the Stable Release Update for metacity has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

Changed in metacity (Ubuntu Utopic):
status: Confirmed → Invalid
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