1. In an extensible editor having an edit designer interface comprising a pre-handle event method, the pre-handle event method comprising: receiving an editing event at the extensible editor, the editing event requesting manipulation of a document; routing the editing event to an editor extension coupled to the extensible editor before the extensible editor acts on the editing event; receiving notification from the editor extension indicating whether the extensible editor should continue to process the editing event after the editing event has been routed to the editor extension; and routing the editing event to an additional editor extension when the notification indicates that the extensible editor should continue to process the editing event, wherein an order in which the editing event is routed to the editor extension and the additional editor extension is based on an order in which the editor extension and the additional editor extension were registered with the extensible editor.