Comment 28 for bug 1625846

I know they don't need to be the same - that's how the workaround 'Xmir -flatten' works. However if they are not the same then the OSK will not function correctly, which is unacceptable. Only acceptable as a temporary workaround...

And we don't need to make the choice to implement X11 window management in Mir, because the Unity8 WM design already requires that we do (indirectly by the missing designed features we haven't implemented yet).

The phrase "the shell" is correct, because that is what is deciding to change the focus to the popup (in the absence of any hint not to). It's also not correct for you to say that "Unity8 is not the X11 window manager". Although I have indeed implemented WM things in Xmir, that is only so much as to pass responsibility for window management on to the shell. Admittedly it's a hybrid approach to attempt to suit Mir's design as well as possible. However in the sense of who owns responsibility for the WM decisions, that is the shell.

We have a Unity8/Mir design document that details a fix, and if we just implement our intended design then this bug will go away.