Column character count when fixed-width pref set for commit message input

Social convention for Git commits at some organizations is like an email body and message, as seen at http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html. For some, this is enforced technically by limiting the first line of the commit to 50 characters and wrapping the rest at 72.

I propose either automating this behavior in SourceTree or providing us with the visual guidelines to do it ourselves. It's really the only thing keeping me from using SourceTree over GitX.

EDIT: I apologize for my stupidity, I just realized we already have fixed-width commits and wrapping. However, my request for limiting the first line in some manner still stands.