Just moved to Ubuntu 18.04 and can confirm the issue and it does seem to be something related to the window manager. I can confirm this only happens with a maximized window and in 16.04 it would happen with gnome but not Unity.
-- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gedit in Ubuntu. https://bugs.launchpad.net/bugs/1573728 Title: Files opened with gedit on command line no longer open within the existing gedit session To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gedit/+bug/1573728/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs