Make the expo view dynamically appear on the focused monitor instead of only on the main monitor

[anaximeno]

Also, the expo view of the workspaces should dynamically move to another monitor if the mouse focus is changed to the other monitor while in the expo view, this should work the same way when you are on the login screen and if you move your mouse to the next monitor the login box, panel, etc, will all move to the next monitor.

Motivation

I often trigger the expo view using gestures and the cursor isn't always on the main monitor, so every time I do that I'll have to move the mouse cursor to the main monitor, move the window I want to change to another workspace, and then, return to the other monitor I was focused in before to continue whatever I was doing.