nsIEditActionListener and addEditActionListener

Question

I'm trying to understand this code:

315       let existingIndex = this._editors.indexOf(editableNode.editor);
316       if (existingIndex == -1) {
317         let x = this._editors.length;
318         this._editors[x] = editableNode.editor;
319         this._stateListeners[x] = this._createStateListener();
320         this._editors[x].addEditActionListener(this);
321         this._editors[x].addDocumentStateListener(this._stateListeners[x]);
322       }

http://mxr.mozilla.org/mozilla-release/source/toolkit/modules/Finder.jsm#320

Especially addEditActionListener(this); what is this? MDN docs say it should be nsIEditActionListener but I can't find what this listener is comprised of MDN docs takes to broken page.

nsIEditor - MDN

Answer 1

this is the Finder object; it implements the nsIEditActionListener interface (http://mxr.mozilla.org/mozilla-release/source/toolkit/modules/Finder.jsm#395)

That interface is defined here: http://mxr.mozilla.org/mozilla-release/source/editor/idl/nsIEditActionListener.idl

So the code essentially attaches the Finder object to the editor, presumably so it can be notified of changes made in the editor at a later point.