OK, it appears to be purely a Unity8/QtMir bug. Unity8 does not allow gaps (splash screens) in the lifecycle of a connection's surface:
Connect Create splash window Destroy splash window Create app window (still using the original connection) This succeeds from the client's perspective (Xmir) but Unity8/QtMir fails to display the second window (which is the main app window). Using other simpler apps I can reproduce the same bug. There's a strange delay in Unity8 -- If you can pause for 5-10 seconds between creating the first and second window then Unity8 does work. Workaround: gimp --no-splash ** Changed in: xorg-server (Ubuntu) Status: Confirmed => Invalid ** Also affects: qtmir (Ubuntu) Importance: Undecided Status: New ** Changed in: qtmir (Ubuntu) Status: New => Confirmed ** Also affects: qtmir Importance: Undecided Status: New ** Changed in: qtmir Status: New => Confirmed -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to unity8 in Ubuntu. https://bugs.launchpad.net/bugs/1501346 Title: Gimp fails to start w/ Xmir running in '-rootless -flatten' mode under Unity 8 Status in QtMir: Confirmed Status in qtmir package in Ubuntu: Confirmed Status in unity8 package in Ubuntu: Confirmed Status in xorg-server package in Ubuntu: Invalid Bug description: I'm trying to run Gimp in a Vivid + overlay PPA Unity 8 desktop session using Xmir from the overlay PPA with the '-rootless -flatten' Xmir options. Gimp fails to start in this situation. I've attached the application and unity8 log files. To manage notifications about this bug go to: https://bugs.launchpad.net/qtmir/+bug/1501346/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp