I'm using the latest version of BTT after not using an earlier version for awhile. Before installing the new one, I had my screenshot function set up so that drawing a rectangle on the screen would capture that area immediately — no further action needed. Then a floating thumbnail for the screenshot would appear for a few seconds in the bottom right corner of the screen, before being deposited on the Mac Desktop. I can't figure out how to activate the floating thumbnail when using BTT.
SOLUTION: Version 4.645 alpha has a setting that solves this problem.