Split out mouse keyboard into separate window

[JuliusSweetland]

Create new indexed class - CompositePointToKeyValueMap which:

• Has indexer (indexed by visual z ordering - if a window is on top it will have a higher z-order index)
• When map is set at a certain z order it will trigger a recalc of the composite map and fire a property changed event
• The MainViewModel can listen to these change events and pass the composite map to the input service
• Any overlapped rects in a map at a certain z order (use Rect.IntersectsWith() to test?) will be excluded from the final map, which will mean that even a slight overlap of two keys will disable the lower (z order) key.

[JuliusSweetland]

Scheduled for inclusion in v3

[alexandre-mbm]

Is this basically the target for the v3 branch?

[JuliusSweetland]

@alexandre-mbm Yes.

[JuliusSweetland]

Closing due to lack of progress. This can be re-opened if required.