I love the Value Preview box (the green background box that shows the final value of a calculated property - you see it all of the place.)
But it can really get in the way sometimes since it is to ubiquitous.
Might I suggest a short cut (Esc key) to close it like you can with the Intellisense (aka code completion) popup?
Another option would be a setting that prevents it form automatically popping up, but you can click an small icon to see it if you want, like the popout code editor.