Checker Plus is a great extension if you want notifications. I explicitly don't want notifications (I wanted to quickly open the compose window and nothing else) which is why I made the simple little extension mentioned in the post.

Five years ago I already had a plan in place to leave my employer and set up my own business (which they were aware of), but was about a year away from my intended leave date. We then got a new boss whose only focus was impressing his superiors as he was told he would be fast tracked for promotion.