/** @return the singleton instance of this frame. */
 public static PreferencesGUIEditorFrame getPreferencesGUIEditorFrame() {
   if (editorFrame != null) editorFrame.setVisible(true);
   return editorFrame;
 }
 /**
  * @return the singleton instance of this frame. If a frame already exists, just returns that one.
  *     otherwise, it creates a new one with the specified prefs configuration.
  * @param prefs: the configuration to use if no frame exists yet.
  */
 public static PreferencesGUIEditorFrame getPreferencesGUIEditorFrame(ClientPreferences prefs) {
   if (editorFrame == null) editorFrame = new PreferencesGUIEditorFrame(prefs);
   editorFrame.setVisible(true);
   return editorFrame;
 }