MC-5622: Unable to input text into TinyMCE4 WYSIWYG area on IE11 in Catalog Product

Author: danielrenaud

lib/web/mage/adminhtml/wysiwyg/tiny_mce/tinymce4Adapter.js

@@ -577,10 +577,10 @@ define([
          * Update text area.
          */
         updateTextArea: function () {
-            var editor = this.activeEditor(),
+            var editor = this.get(this.getId()),
                 content;
 
-            if (!editor) {
+            if (!editor || (editor.id !== this.activeEditor().id)) {
                 return;
             }