remove the 'comment' option from CKEditor's contextmenu in when UI is locked

www/pad/comment.js

@@ -13,6 +13,18 @@
         return b;
     }
 
+    // COPYPASTED from mediatag-plugin-dialog.js
+    var isReadOnly = function (el) {
+        if (!el) { return; }
+        var parent = el;
+        while (parent) {
+            if (parent.nodeName.toUpperCase() === 'BODY') {
+                return parent.getAttribute("contenteditable") === 'false';
+            }
+            parent = parent.parentElement;
+        }
+    };
+
     var color1 = 'rgba(249, 230, 65, 1.0)';
     var color2 = 'rgba(252, 181, 0, 1.0)';
 
@@ -164,7 +176,8 @@
                 */
                 editor.contextMenu.addListener(function(element, sel, path) {
                     var applicable = isApplicable(path, sel);
-                    if (!applicable) { return; }
+                    if (!applicable || isReadOnly(element.$)) { return; }
+
                     return {
                         comment: CKEDITOR.TRISTATE_OFF,
                     };