rem: var deck = document.getElementById("displayDeck"); var nowSelected = null; try { nowSelected = deck.selectedPanel.id; } catch (ex) { } 
add: var selectedPanel = document.getElementById("displayDeck").selectedPanel; var nowSelected = selectedPanel ? selectedPanel.id : ""; 
context: function ObserveDisplayDeckChange(event){  var deck = document.getElementById("displayDeck");  var nowSelected = null;  try { nowSelected = deck.selectedPanel.id; } catch (ex) { }  if (nowSelected == "threadPaneBox")    ShowingThreadPane();  else    HidingThreadPane();    if (nowSelected == "accountCentralBox")    ShowingAccountCentral();  else    HidingAccountCentral();}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/e29db857d189867d3ded0ecde46ba40049e5b40c/mailWindow.js/clean/mail/base/content/mailWindow.js