clear item selection before refreshing to work around wierd tree bug

mailnews/base/prefs/resources/content/SmtpServerList.js

@@ -107,6 +107,8 @@ function refreshServerList()
 {
     // save selection
     var oldSelectedIds = new Array;
+    serverList.clearItemSelection();
+    serverList.clearCellSelection();
     var selectedItems = serverList.selectedItems;
     for (var i=0; i< selectedItems.length; i++)
         oldSelectedIds[i] = selectedItems[0].id;