/** Updates buttons and status based on current libraries */
 public void update() {
   updateButtons();
   IStatus status = Status.OK_STATUS;
   EnvironmentVariable[] standins = fEnvironmentVariablesContentProvider.getStandins();
   for (int i = 0; i < standins.length; i++) {
     IStatus st = standins[i].validate();
     if (!st.isOK()) {
       status = st;
       break;
     }
   }
   updateDialogStatus(status);
 }