bomberstudios/sketch-commands — pull request #33 by tarngerine (2014-02-15 01:55:03+00:00)
Title: Equalize width/height UP and DOWN

I had done it before I submitted this issue:
https://github.com/bomberstudios/sketch-commands/issues/31

but your suggestion for holding ALT is interesting too. Personally I prefer this as it's clearer to new users (holding alt is kind of secret)