Be able to see the frames before

Feature Suggestions
#1

I think it would be helpful if you could add a feature where you could see the frames that happened before the frame that you are working on now. It would make animating alot easier

#2

Is it something like this?

http://forum.wickeditor.com/t/setting-transparency-and-colour-for-onion-skin/842/2

#3

it already exists its called the onion skin