OK - sounds as if there is a problem - hope it gets fixed soon.
I tried downgrading to the previous versions of xserver-xorg-xmir and xserver-xorg-core (2:1.15.0-1ubuntu2), but no help.
Then I removed ubuntu-desktop-xmir (and xserver-xorg-xmir) and all is well again.
OK - sounds as if there is a problem - hope it gets fixed soon.
I tried downgrading to the previous versions of xserver-xorg-xmir and xserver-xorg-core (2:1.15. 0-1ubuntu2) , but no help.
Then I removed ubuntu-desktop-xmir (and xserver-xorg-xmir) and all is well again.