I'd select the section I'd want to crop, copy it, create a new image, resize it to 1x1 or something else small, then paste. The canvas would automatically resize to fit the pasted selection. It sounds a bit more involved than your version, but for me it worked.
Re:JS Paint – A web-based MS Paint remake
by TeMPOraL on Thursday January 18, 2018 @04:29AM
(#16175809)
Yeah, I noticed this mechanism (probably even used it a few times), but I eventually gravitated towards something with less clicking.
I do that in Paint.NET a lot, though. I select the part of the image I'm interested in, and then in two keyboard presses (CTRL+C, ALT+CTRL+V, AFAIR) I copy it and "paste into new image".
"That's how Dad did it, that's how America does it, and it's worked out pretty well so far."