support "get first click", aka xmouse aka acceptsFirstMouse

[mark-pictor-csec]

With windows and linux, I'm used to applications seeing a click in their window even if they were not in the foreground before the click. The OSX default behavior is that apps do not get these events.

It is possible to change the behavior:

[...] See -acceptsFirstMouse: in NSView

-- superuser.com comment

This would result in a more seamless experience in most guest OSes/apps, with fewer clicks necessary. I suspect there would be cases in which it was undesirable, so I'd make it possible to disable.

It'd also be nice if the guest cursor could follow the host cursor even when the guest window is not in the foreground; I don't know if acceptsFirstMouse has an impact on that or not. Currently, the guest cursor stays at the edge of the window until I mouse over the utm window, click (to activate said window), and move the mouse some more. If I click a second time without first moving the mouse, the click event happens without the guest cursor moving (i.e. near the edge of the virtual screen), rather than where I actually clicked.