There should be multiple start tabs to begin a quiz. It is to easy to hit the tab by accident and start a quiz merely by accident or because of a lag in page loading that starts quiz due to a early left click in anticipation of a next or previous button.
A single stroke quiz start is obviously a bad idea. It's like a single hit key that resets your computer, there's no going back.
Thanks (Front Range CC uses D2L and it looks ancient and is really basic but it is a very user friendly from the get go. We don't care if it is fancy. We want obvious, clear, and easy to use. Too many layers involved for the interface on canvas.