--- a/suite/mailnews/mailWindowOverlay.js
+++ b/suite/mailnews/mailWindowOverlay.js
@@ -812,17 +812,18 @@ function InitMessageMark()
      flaggedItem.setAttribute("checked", areMessagesFlagged);
 
   document.commandDispatcher.updateCommands('create-menu-mark');
 }
 
 function UpdateJunkToolbarButton()
 {
   var junkButtonDeck = document.getElementById("junk-deck");
-  junkButtonDeck.selectedIndex = SelectedMessagesAreJunk() ? 1 : 0;
+  // Wallpaper over Bug 491676 by using the attribute instead of the property.
+  junkButtonDeck.setAttribute("selectedIndex", SelectedMessagesAreJunk() ? 1 : 0);
 }
 
 function UpdateDeleteCommand()
 {
   var value = "value";
   var uri = GetFirstSelectedMessage();
   if (IsNewsMessage(uri))
     value += "News";