Defined Size Selection :: Pixelmator v Acorn v Photoshop v GIMP

Creating a defined selection box of X pixels by Y pixels
Pixelmator: No
Acorn: Yes
Photoshop: Yes (link is to one description of doing this in an older version, but I expect it’s been substantially carried forward.)
GIMP: Yes

In my efforts at work to find a Photoshop alternative with a significantly lower cost, I’ve purchased both Pixelmator and Acorn. Last fall I worked mostly with Acorn, and I’m hoping to use Pixelmator more this fall with the DOCC node I work with.

Update 30 Apr 2015: Added GIMP