[Affected versions]: Firefox 57.0b11 (BuildId:20171023180840) Firefox 58.0a1 (BuildId:20171025230440) [Affected platforms]: - Ubuntu 14.04 64bit - Ubuntu 12.04 32bit [Unaffected platforms]: - Ubuntu 16.04 64bit - macOS 10.12 - Windows 10 64bit [Steps to reproduce]: 1. Launch Firefox. 2. Access the Customize panel. 3. Drag two items in the overflow panel. 4. Exit the Customize mode. 5. Open the Overflow menu. 6. Unpin 1 of the item. [Expected result]: The item is successfully unpinned and no issues are encountered. [Actual result]: The item is unpinned but graphical issues can be seen. [Regression range]: This seems like a regression. I will get back with this as soon as time permits. [Additional notes]: Form more information regarding this issue please observe the following screencast:https://drive.google.com/open?id=0B94iuIVMr-TEbDlwLUg3VEwyTVE

Milan, how extensive is our graphics support for older versions of Linux/GTK ? Given that this is Linux-only and only reproduces on old OSes, not sure how important this is (and maybe this needs to move to Widget/GTK, but I don't know enough to make that call). Emil, how sure are you about this being a regression (other than, perhaps, the functionality not working the same way previously)? This feels like a platform bug to me. Perhaps one that we only exposed recently, but it seems unlikely that the bug itself is recent...

We've also already wontfixed bug 1411978, I wouldn't be opposed to doing the same here.

The following pushlog was generated using mozregression: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=5a63d8457a2a69a2ad54a50765bff412580df2a4&tochange=14db7c0bcf9ae86c9ec2cc9d3c249a42e459a2a9 Please let me know if this helps.

Not tracking this for photon cleanup.