Make window mouse events consistent when views are present

[capr]

Current situation:

Windows: behaves as if the window has a hole around the view (i.e. the window receives mouseleave when moving from the window area to the view area and viceversa -- it gets mouseenter when moving from the view area to the window area).
OSX: behaves as if the view is not even there (the window doesn't receive mouseleave when moving from window area to view area).
X11: behaves like Windows, but with an added dose of crazy as usual: when moving the mouse directly from a different window over a view, it causes both the window and the view to receive mouseenter events.

Solutions:

• easy/logical: emulate Windows behavior in OSX, see if we can fix X11 mouseenter blunder
• hard/benefits not apparent: emulate OSX behavior in X11 and Windows