Don't mistake an attribute for a property.

Bug 478800 - Drop-down 'View:' menu displays 'undefined' when you try and use Tags, or Custom Views.
r+moa=mnyromyr

suite/mailnews/msgViewPickerOverlay.js

@@ -155,7 +155,7 @@ function GetLabelForValue(aValue)
       RefreshAllViewPopups(viewPickerPopup, true);
       selectedItems = viewPickerPopup.getElementsByAttribute("value", aValue);
     }
-    label = selectedItems && selectedItems.length && selectedItems.item(0).label;
+    label = selectedItems && selectedItems.length && selectedItems.item(0).getAttribute("label");
   }
   return label;
 }