An extensible editor allows integration of extensions that modify the editor's default behavior and provide customized feedback to users. The editor includes an event routing model that works to decrease the occurrence of conflicts between the editor and extensions and between extensions. Upon the occurrence of an event, the editor routes the event to each extension before the editor's default handling of the event occurs. When an extension responds to an event, the extension may “consume” the event by indicating to the editor not to allow further processing of the event. After an event has been pre-processed by each extension, the default editor acts on the event. The editor then routes the event to each extension again, to allow each extension to process the event after the default editor has acted.