Enumeration prefs_enum = t.getPreferences();
Enumeration prefs_enum; synchronized (t) { prefs_enum = t.getPreferences(); }
  public void replacePreference(NewTask t, Preference new_pref) {    // Remove the preference from the current list of     // preferences for this task    Enumeration prefs_enum = t.getPreferences();    Vector this_task_prefs = UTILAllocate.enumToVector(prefs_enum);    t.setPreferences((replacePreference(this_task_prefs,					new_pref)		      ).elements());  }