@pdnnoob:
The problem with using your method is that it doesn't keep the aspect ratio fixed when re-sized. This is very bad when working with web images and logos, for example.
Do you have a solution that would allow you to fix the aspect-ratio in such a partial image re-size?
If not, would that be something Paint.NET would consider implementing? (When?)
Thanks in advance.
EDIT:
I just found the answer here: Hold down SHIFT while moving the "Move Selected Pixels" knobs! Excellent!