Affected versions

• Firefox 74.0
• Firefox 75.0b4
• Firefox 76.0a1

Affected platforms

• macOS 10.15

Steps to reproduce

1. Launch Firefox
2. Access Janus Webrtc
3. Click on Start, insert a title for the room and then click on share your screen.
4. At the window selection, choose Screen 2 and accept the permissions

Expected result

• Screen is shared without any issue

Actual result

• Only a part of the screen is actually shared, while the rest is frozen

Regression range

• I will see for a regression

Additional notes

• The issue can be seen in the attachment
• This was reproducible on a macbook, with a dual display setup.
• Both Windows and Ubuntu seems not to be affected

Bugbug thinks this bug is a regression, but please revert this change in case of error.

Do we know if this happens on ESR68?

Yep, 68.6.0esr is also affected.

Hey Dan, are you still planning to address this one for FX 77?

I'm not sure if I will have time for this, I'm pretty busy with Bug 1164187. Nico, is there any chance you could have a look at this one?

Sure, I can take a look.

Do you have an update here Nico?

I think I may have finally been able to reproduce this issue. For me, if there is nothing on the second screen, only a portion of menus will appear. I will try get a regression range. I can reproduce this on 10.14. It appears that the bounds of the update area is inconsistent on the second screen.

I tried searching a regression for this, but it turns out that it will be broken on builds as early as the first months of 2017. Trying older builds than that, will refuse to share the screen at all, as the page will remain white.

Nico, did you end up finding what's up here?

Perhaps. I was just talking to Dan yesterday about a seemingly extra crop and scale we are doing for ScreenSharing in MediaEngineRemoteVideo. I think what I was able to reproduce may be a second unrelated problem.