Need a way to catch undo/redo (and cancel) in WebKit
HTML editing libraries at Google need a way to catch undo/redo (besides just listening for the DOM mutation events) so that they can keep internal state relating to the document, beyond just the HTML. Without being able to catch these mutating events (and ideally canceling them!) WebKit just smashes over the DOM and the HTML editing libraries have to clean up after it.
HTML5 has some nascent undo/redo apis:
but we're going to need something a bit more full featured in the future.