Glass Robot and getSCreenCapture

[David DeHaven]

> For a one shot screen capture - we would pass in top left and width and height to make the bottom right.
> Currently this should work on Mac I am told, though what is in the out of bounds pixels is not known.
> And if we added a third "tall" screen to the left, life gets even more complicated :-(

When pressing Command+Shift+3, the Mac creates separate images for each display.

-DrD-