I and hopefully many others edit their Additional CSS definitions quite frequently for testing purposes.
Its a HELL lot of pain to go to Main CSS and then SCROLL ALL THE WAY DOWN everytimeee. (I hope I am not missing any shortcut, if already exists)
I request Additional CSS Definitions (those two text area fields ALONE) to be put in the Style Manager dropdown. When Stylevars can have their own page (which is used less often), then WHY NOT additonal CSS definitions??