Affected versions

• Firefox 87.0b7
• Firefox 88.0a1

Affected platforms

• Ubuntu 20.04

Preconditions

• Two display setup

Steps to reproduce

1. Launch Firefox
2. Have a main Firefox window on a screen
3. Have a second Firefox window on the other one and access customize in it
4. Select Title bar option

Expected result

• The windows remain on the displays were they were originally opened

Actual result

• Both the windows are dragged on the upper left side of one display

Regression range

• Will see for a regression

Additional notes

• The issue can be seen in the attachment.
• macOS and Windows are not affected by this

(In reply to Catalin Sasca, QA [:csasca] from comment #0)

• The issue can be seen in the attachment.

I don't really know what file is meant to be in the attachment or how to open it, can you update the mimetype?

• macOS and Windows are not affected by this

I think this is an issue with the gtk widget csd implementation.

I don't know why it isn't having an extension, but I was able to open the attachment by simply dragging it in Firefox or Chrome. Let me know if you can open it too.

(In reply to Catalin Sasca, QA [:csasca] from comment #2)

I don't know why it isn't having an extension, but I was able to open the attachment by simply dragging it in Firefox or Chrome. Let me know if you can open it too.

I cannot. I just get offered a download of an extensionless file, and with application/octet-stream mimetype I'm 100% confident that the best Firefox will do is offer a download, not opening it, so I don't understand what you mean here.

Please clarify the mimetype using the appropriate field on bugzilla.

This is not a regression. When titlebar is switched on/off we need to hide/show the window and re-create it as window manager can't change the decorations on the fly. We can't do anything about it, it's by design.