Index: /branches/release-39/default_templates/javascript.mtml
===================================================================
--- /branches/release-39/default_templates/javascript.mtml (revision 2486)
+++ /branches/release-39/default_templates/javascript.mtml (revision 2487)
@@ -604,5 +604,9 @@
     checkbox.value = parent_id; 
     checkbox.checked = true;
-    text.focus();
+    try {
+        // text field may be hidden
+        text.focus();
+    } catch(e) {
+    }
 
     mtSetCommentParentID();