Comment 20 for bug 1488417

Comment #18 kind of makes sense.

In trying to replicate the bug using just Mir demos I found one way to do it: Have a client (which in our case is Unity8 itself) that fails to resize to cover all displays. As it fails to resize to cover all displays, the client (Unity8 shell) will fail to get motion events that are outside of its window.

So this problem can be solved in Unity8 by resizing the Unity8 Mir surface to cover all displays, or it can be solved more reliably with a Mir enhancement (which we plan on already) --> implement pointer grabs so that the cursor location does not ever stop the owning surface from receiving pointer events.

Either way, seems like Mir is working correctly. In the absence of pointer grab support, clients (including Unity8) stop getting pointer events when the cursor leaves their window.