fix author layer getting lost when moving tab between panes

plugins/c9.ide.collab/author_layer.js

@@ -38,9 +38,17 @@ define(function(require, module, exports) {
         function AuthorLayer(session) {
             var plugin = new Plugin("Ajax.org", main.consumes);
             // var emit = plugin.getEmitter();
-            var marker = session.addDynamicMarker({ update: drawAuthInfos }, false);
+            var marker;
 
             function refresh() {
+                if (showAuthorInfo) {
+                    session.on("changeEditor", onChangeEditor);
+                    marker = session.addDynamicMarker({ update: drawAuthInfos }, false);
+                }
+                else {
+                    dispose();
+                }
+                
                 var doc = session.collabDoc.original;
                 var ace = doc.editor && doc.editor.ace;
                 var aceSession = ace && ace.session;
@@ -48,15 +56,33 @@ define(function(require, module, exports) {
                     return;
 
                 session._emit("changeBackMarker");
-                var renderer = ace.renderer;
+                onChangeEditor({ editor: ace });
+            }
+
+            function dispose() {
+                marker && session.removeMarker(marker.id);
+                session.off("changeEditor", onChangeEditor);
+            }
+
+            plugin.freezePublicAPI({
+                get colorPool() { return workspace.colorPool; },
+                refresh: refresh,
+                dispose: dispose
+            });
+
+            return plugin;
+        }
+        
+        function onChangeEditor(e) {
+            var renderer = (e.editor || e.oldEditor).renderer;
             renderer.$gutterLayer.$padding = null;
             renderer.$loop.schedule(renderer.CHANGE_GUTTER);
-                if (showAuthorInfo) {
+            if (showAuthorInfo && e.editor) {
                 renderer.$gutterLayer.on("afterRender", decorateGutter);
             }
             else {
                 renderer.$gutterLayer.off("afterRender", decorateGutter);
-                    clearGutterDecorations(renderer);
+                clearGutterDecorations(renderer.$gutterLayer);
             }
         }
 
@@ -119,14 +145,15 @@ define(function(require, module, exports) {
             var doc = session.collabDoc;
             var isCollabGutter = doc && showAuthorInfo && util.isRealCollab(workspace);
 
+            if (!isCollabGutter)
+                return;
+            
             var config = gutter.config;
             var range = new Range(config.firstRow, 0, config.lastRow, Number.MAX_VALUE);
             var authorKeysCache = isCollabGutter && createAuthorKeyCache(editorDoc, doc.authAttribs, range).authorKeys;
             var colorPool = workspace.colorPool;
             var reversedAuthorPool = workspace.reversedAuthorPool;
             
-                if (!isCollabGutter)
-                    return clearGutterDecorations();
             var cells = gutter.$lines.cells;
             for (var i = 0; i < cells.length; i++) {
                 var cell = cells[i];
@@ -144,9 +171,9 @@ define(function(require, module, exports) {
             }
         }
         
-            function clearGutterDecorations(renderer) {
-                renderer.$gutterLayer.$lines.cellCache.length = 0;
-                var cells = renderer.$gutterLayer.$lines.cells;
+        function clearGutterDecorations(gutter) {
+            gutter.$lines.cellCache.length = 0;
+            var cells = gutter.$lines.cells;
             for (var i = 0; i < cells.length; i++) {
                 var cell = cells[i];
                 cell.element.style.borderLeft = "";
@@ -219,19 +246,6 @@ define(function(require, module, exports) {
             };
         }
 
-            function dispose () {
-                session.removeMarker(marker.id);
-            }
-
-            plugin.freezePublicAPI({
-                get colorPool() { return workspace.colorPool; },
-                refresh: refresh,
-                dispose: dispose
-            });
-
-            return plugin;
-        }
-
         function getLineAuthorKey(session, authAttribs, row) {
             var editorDoc = session.doc;