A Rich Internet Application without undo/redo is like a series of trap-doors: your users had better be sure about every move, because there's no going back. Implementing undo/redo isn't as difficult as you might think. In this article I'll walk you through the basics, using my Pixton comic editor as the example application. These concepts can be applied to any application that lets its users do things they might regret - or unregret!
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