I have been for years using
shift+cmd+4 to take a screenshot of only a part of the screen, or just to measure some distance in an image. A week or so ago it completely changed functionality to instead take a screenshot of the entire hovered window... Why?? I need it back.. I get designs as JPG's :D and need to implement websites base on that :P
I haven't installed anything that I can think of, I got a new external screen but that was plug & play, a DELL screen. It can't be that can it??
Attaching a photo of how it looks below, note the blue tint that the window is selected and the camera icon in the middle..