Fix for documents refCount issue

src/document/Document.js

@@ -200,16 +200,14 @@ define(function (require, exports, module) {
      * @param {!Editor} masterEditor
      */
     Document.prototype._makeEditable = function (masterEditor) {
-        if (this._masterEditor) {
-            //Already a master editor is associated , so preserve the old editor in list of full editors
-            if (this._associatedFullEditors.indexOf(this._masterEditor) < 0) {
-                this._associatedFullEditors.push(this._masterEditor);
-            }
-        }
 
         this._text = null;
         this._masterEditor = masterEditor;
 
+        if (this._associatedFullEditors.indexOf(this._masterEditor) < 0) {
+            this._associatedFullEditors.push(this._masterEditor);
+        }
+
         masterEditor.on("change", this._handleEditorChange.bind(this));
     };
 
@@ -252,6 +250,24 @@ define(function (require, exports, module) {
         }
     };
 
+
+    /**
+     * Checks and returns if a full editor exists for the provided pane attached to this document
+     * @param {String} paneId
+     * @return {Editor} Attached editor bound to the provided pane id
+     */
+    Document.prototype._checkAssociatedEditorForPane = function (paneId) {
+        var editorCount, editorForPane;
+        for (editorCount = 0; editorCount < this._associatedFullEditors; editorCount++) {
+            if (this._associatedFullEditors[editorCount]._paneId === paneId) {
+                editorForPane = this._associatedFullEditors[editorCount];
+                break;
+            }
+        }
+
+        return editorForPane;
+    };
+
     /**
      * Disassociates an editor from this document if present in the associated editor list
      * To be used internally by Editor only when destroyed and not the current master editor for the document

src/editor/EditorManager.js

@@ -541,11 +541,14 @@ define(function (require, exports, module) {
     function _showEditor(document, pane, editorOptions) {
         // Ensure a main editor exists for this document to show in the UI
         var createdNewEditor = false,
-            editor = document._masterEditor;
-
-        //Check if a master editor is not set already or the current master editor doesn't belong
-        //to the pane container requested - to support creation of multiple full editors
-        if (!editor || editor._paneId !== pane.id) {
+            // Check if any full editor is present marked for the requested pane
+            // This check is required as _masterEditor is the active full editor for the document
+            // provided and there can be existing full editor created for other panes
+            editor = document._checkAssociatedEditorForPane(pane.id) || document._masterEditor;
+
+        // Check if a master editor is not set already or the current master editor doesn't belong
+        // to the pane container requested - to support creation of multiple full editors
+        if (!editor || (editor._paneId && editor._paneId !== pane.id)) {
             // Performance (see #4757) Chrome wastes time messing with selection
             // that will just be changed at end, so clear it for now
             if (window.getSelection && window.getSelection().empty) {  // Chrome