Monocle should be able to support multiple Screens. Currently only a single screen, /dev/fb0 is supported.
We use /dev/fb1 as the cursor overlay, and I expect that will need to be configurable with multiple screens.

There will need to be a choice on some technical issues, mostly understanding what JFX does naturally, and what changes would need to be made to the window management built in to Monocle.

Changes will need to be made in:
   * MonocleScreen
      * to detect (optionally?) the additional displays and report them
      * to select the primary display (fb0, env override?)
   * MonocleWindow
      * use the provided screen to create the window.
Flush out hardcoded references elsewhere.

Would we need two window stacks ? Quantum does a painters algorithm on a Screen, so that would probably need some level of rework.