Make sharing a single window work with Jitsi in Firefox

[marmarek]

The problem you're addressing (if any)
Jitsi (and other video conference software) allows desktop sharing. This includes convenient feature of sharing a single window. When running under Qubes, only "entire screen" option is present. Of course this "entire screen" in practice includes only content from that single VM.

Describe the solution you'd like
Adjust gui-agent-linux to set necessary metadata to enable enumerating windows/applications in a format that normal window manager does.

Where is the value to a user, and who might that user be?
More useful desktop sharing.

Additional context
Firefox code using for window enumeration: https://hg.mozilla.org/mozreview/gecko/file/tip/media/webrtc/trunk/webrtc/modules/desktop_capture/window_capturer_x11.cc
Specifically this is interesting:

  // Iterates through |window| hierarchy to find first visible window, i.e. one
  // that has WM_STATE property set to NormalState.
  // See http://tronche.com/gui/x/icccm/sec-4.html#s-4.1.3.1 .
  ::Window GetApplicationWindow(::Window window);

Windows within Qubes VMs do not have WM_STATE property. According to linked documentation there, it is responsibility of a window manager (gui-agent in this case).

Workaround

Manually set WM_STATE property on a window you want to share:

xprop -f WM_STATE 32c -set WM_STATE 1

(and click on the window)

Relevant documentation you've consulted

http://tronche.com/gui/x/icccm/sec-4.html#s-4.1.3.1

Related, non-duplicate issues
A list of links to other bug reports, feature requests, or tasks in the qubes-issues tracker. Do not describe any other unreported bugs, features, or tasks here.

[Rudd-O]

It does seem like WM_STATE is a property that the window manager ought to respect / set.

Alternatively how about we push forward to Wayland?

[marmarek]

It does seem like WM_STATE is a property that the window manager ought to respect / set.

Yes, exactly. And in case of AppVM, window manager = qubes-gui-agent.

Alternatively how about we push forward to Wayland?

This is tracked here: #3366

[xaki23]

as a sidenote: this works for google meet on firefox too.
thanks!

[iamahuman]

This also affects Wine; specifically, there's a few seconds of delay before a window is opened or closed.

This is what I'm using as a workaround: https://gist.github.com/iamahuman/34bd91b9815fb2cc5de72028d39d223c

The script acts as a "stub" window manager and handles the WM_STATE transition which the GUI agent lacks.

I shall perhaps also add this to https://github.com/Qubes-Community/Contents sooner or later...

[qubesos-bot]

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The package gui-agent-linux has been pushed to the r4.1 testing repository for the CentOS centos8 template.
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The package qubes-gui-agent_4.1.15-1 has been pushed to the r4.1 testing repository for the Debian template.
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Automated announcement from builder-github

The package gui-agent-linux has been pushed to the r4.0 testing repository for the CentOS centos8 template.
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[qubesos-bot]

Automated announcement from builder-github

The package gui-agent-linux has been pushed to the r4.1 stable repository for the CentOS centos8 template.
To install this update, please use the standard update command:

sudo yum update

Changes included in this update

[qubesos-bot]

Automated announcement from builder-github

The component gui-agent-linux (including package pulseaudio-qubes-4.1.16-1.fc32) has been pushed to the r4.1 stable repository for the Fedora template.
To install this update, please use the standard update command:

sudo yum update

Changes included in this update

[qubesos-bot]

Automated announcement from builder-github

The package pulseaudio-qubes-4.1.16-1.fc32 has been pushed to the r4.1 stable repository for dom0.
To install this update, please use the standard update command:

sudo qubes-dom0-update

Or update dom0 via Qubes Manager.

Changes included in this update