1637327 - List of application windows for screensharing is incomplete on Linux

Status: NEW

(Core :: WebRTC: Audio/Video, defect, P3)

Description

[robert]

Attachment: Screenshot with Okular and Firefox. The full screen slide in the background cannot be selected in Firefox.

Dear all,

I am not sure where to look for the problem. Please direct me towards the root of the issue if you know better.

Problem:

I cannot share in Video conferences with Cisco Webex or Meet.Jitsi (both WebRTC based) full screen PDF slides without sharing the entire screen and without having the PDF fullscreen in the front. That means, I cannot see my next slide or the chat during my talk.

To reproduce:

1. open any PDF with okular PDF viewer (on Linux)
2. switch to full screen.
3. notice that a 2nd window is opened which shows no control elements, but just the PDF
4. open Firefox (or Chromium), navigate to https://mozilla.github.io/webrtc-landing/gum_test.html and click Screen Capture to simulate e.g. sharing slides during a video conference with tools such as Meet.Jitsi or bigBluebutton etc.
5. Both tested browsers present a list of application windows that can be shared, that does not contain the full screen window with the slides, but only the main window of Okular.

I have also filed a bug report to the Okular dev community:
https://bugs.kde.org/show_bug.cgi?id=421206

Ideas: Maybe Firefox filters the application window list and only shows primary app windows instead of all app windows.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Dan Minor [:dminor]]

Thank you for the bug report. Marking this as confirmed based upon the screenshot.

I would be interested in hearing what the Okular developers have to say. In gnome, using evince in presentation mode, I'm able to select the full screen window and share it as expected. I'm not saying you should switch to gnome, just that okular must be handling its presentation mode differently. From your bug description, it sounds like both Firefox and Chromium are unable to pick the window. Is that the case?

Comment 3

[robert]

Indeed, I face the same problem with Firefox and Chromium.

Comment 4

[Daniel Bodea [:danibodea]]

This is also reproduced in Beta v77.0b9 and Nightly v78.0a1 on Ubuntu 18.04.4LTS.

Comment 5

[s]

I have this problem in version 80: I will be using BigBlueButton for a presentation at KDE Akademy, several days from now; but because I can't select the window containing my slides, I guess I have to share the whole screen instead, which requires me to only use one monitor, and then BigBlueButton itself (in my Firefox window) will also be shared along with it, until I cover that up by putting the slides fullscreen on top of it. That's really not ideal.

My slides are written in QML. The window I can't select is the one that the qml runtime creates.

Please increase the priority of this bug.

Comment 6

[s]

Attachment: mozilla-bug-1637327.png

Comment 7

[debus]

Cannot reproduce it anymore. Do you still experience the issue with more recent versions of Okular and Firefox?

Comment 8

[Kishore G]

(In reply to debus from comment #7)

Cannot reproduce it anymore. Do you still experience the issue with more recent versions of Okular and Firefox?

I can still reproduce it on X11.
Okular 22.03.90
Firefox 99.0.1
Window manager: kwin 5.24.4

On Wayland, where xdg-desktop-portal is used, the bug is not reproducible.

Comment 9

[robert]

I can still reproduce it on X11.
Okular 21.12.3
Firefox 98.0.2 (64-bit)

I am on OpenSuse Tumbleweed.