17. The method as recited in claim 15 , further comprising receiving an additional signal from the second extension indicating whether to continue processing the event, and processing the event if the additional signal indicates that processing should continue.
15. A method for processing events in an extensible editor that communicates with a first extension and a second extension, the method comprising: sending an editing event requesting manipulation of a document to the first extension; receiving a signal from the first extension indicating whether to continue processing the event; and sending the editing event to the second extension when the signal indicates that processing should continue, wherein an order in which the editing event is routed to the first extension and the second extension is based on an order in which the first extension and the second extension were registered with the extensible editor.