Comment 49 for bug 1672297

It might have been fixed in a series of changes made in mutter (future version) 3.26.3. It's just unusual and unexpected that Gnome has not done a release for months, so we have not yet tried those fixes. Instead, it looks like we will jump to 3.28 now, soon. So if bionic goes well with 3.28 then we will seriously consider backporting the leak fixes to artful.

This is also one of those bugs that could be subjective. A fix that works for one person might not work for the next. So I guess in order to make sure everyone is on the same page, please ensure you have not installed any Gnome Shell extensions beyond the default Ubuntu ones. Because we don't want to get caught up debugging a gnome-shell extension that most people don't use.

P.S. I stopped working on this bug because I stopped being able to reproduce it.