Capture from a background window without raising it to focus.

[keyosuke]

I love this utility for capturing a screenshot of a website that periodically updates and discarding the screenshot if there was no change, but it would be more useful to me if there was a way to capture the same region of the same window without necessarily raising it to focus, so the focus change doesn't interfere with other things going on in that login session.

I know it's possible because I've done screen capture of things that don't have focus, and I know it doesn't work in all circumstances, but maybe this could be a new option.