diff --git a/common/modules/dom.jsm b/common/modules/dom.jsm
index 5d3bb29e..847fa3b9 100644
--- a/common/modules/dom.jsm
+++ b/common/modules/dom.jsm
@@ -415,7 +415,7 @@ var DOM = Class("DOM", {
         return editor;
     },
 
-    get isEditable() !!this.editor,
+    get isEditable() !!this.editor || this.style.MozUserModify == "read-write",
 
     get isInput() isinstance(this[0], [Ci.nsIDOMHTMLInputElement,
                                        Ci.nsIDOMHTMLTextAreaElement,