Hi Timo, To test I removed the package holds, updated and upgraded to current released packages, and then rebooted. At this point I confirmed the issue in the original report.
Next I enabled the xenial-proposed repository, updated and then installed the following two packages: sudo apt install xserver-common/xenial-proposed xserver-xorg-core /xenial-proposed Then I rebooted. After reboot I confirmed that these proposed xenial packages did indeed fix the issue. I was once again able to click on the three line/bar icon in Firefox and see the drop down menu list display. I also confirmed that there were no regressions in my testing (no SDDM hang on login, and no screen tearing). Following is the output you requested earlier. $ apt-cache policy xserver-xorg-core xserver-xorg-core: Installed: 2:1.18.4-0ubuntu0.8 Candidate: 2:1.18.4-0ubuntu0.8 Version table: *** 2:1.18.4-0ubuntu0.8 400 400 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages 100 /var/lib/dpkg/status 2:1.18.4-0ubuntu0.7 500 500 http://ca.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages 500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages 2:1.18.3-1ubuntu2 500 500 http://ca.archive.ubuntu.com/ubuntu xenial/main amd64 Packages $ Thank you very much for fixing this problem and seeing it through to xenial-proposed. If there is any more steps you need me to take to get this into an official release package then please let me know. Sincerely, Curtis Gedak ** Tags removed: verification-needed -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1780664 Title: Recent libgl-mesa graphics update prevents drop down list menu appearing in apps like firefox three line/bar menu icon To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1780664/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp