Program: 1212
Project: 1212
Buggy source:
public UISelectWorldMenu(){
  maximaze();
  _overlay=new UIImageOverlay("String_Node_Str");
  _overlay.setVisible(true);
  _window=new UIDialogCreateNewWorld("String_Node_Str",new Vector2f(512f,256f));
  _window.center();
  _window.setModal(true);
  GUIManager.getInstance().addWindow(_window,"String_Node_Str");
  _list=new UIList(new Vector2f(512f,256f));
  _list.setVisible(true);
  _list.addDoubleClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      loadSelectedWorld();
    }
  }
);
  ConfigObject config=null;
  String path=Terasology.getInstance().getWorldSavePath("String_Node_Str");
  File worldCatalog=new File(path);
  for (  File file : worldCatalog.listFiles(new FileFilter(){
    public boolean accept(    File file){
      if (file.isDirectory()) {
        return true;
      }
 else {
        return false;
      }
    }
  }
)) {
    File worldManifest=new File(file.getPath() + "String_Node_Str");
    try {
      config=new ConfigSlurper().parse(worldManifest.toURI().toURL());
      if (config.get("String_Node_Str") != null && config.get("String_Node_Str") != null) {
        _list.addItem((String)config.get("String_Node_Str"),config);
      }
    }
 catch (    MalformedURLException e) {
      Terasology.getInstance().getLogger().log(Level.SEVERE,"String_Node_Str",e);
    }
  }
  _goToBack=new UIButton(new Vector2f(256f,32f));
  _goToBack.getLabel().setText("String_Node_Str");
  _goToBack.setVisible(true);
  _loadFromList=new UIButton(new Vector2f(128f,32f));
  _loadFromList.getLabel().setText("String_Node_Str");
  _loadFromList.setVisible(true);
  _createNewWorld=new UIButton(new Vector2f(192f,32f));
  _createNewWorld.getLabel().setText("String_Node_Str");
  _createNewWorld.setVisible(true);
  _deleteFromList=new UIButton(new Vector2f(128f,32f));
  _deleteFromList.getLabel().setText("String_Node_Str");
  _deleteFromList.setVisible(true);
  _createNewWorld.addClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      GUIManager.getInstance().setFocusedWindow(_window);
    }
  }
);
  _deleteFromList.addClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      if (_list.getSelectedItem() == null) {
        GUIManager.getInstance().showMessage("String_Node_Str","String_Node_Str");
        return;
      }
      try {
        ConfigObject config=(ConfigObject)_list.getSelectedItem().getValue();
        String path=Terasology.getInstance().getWorldSavePath((String)config.get("String_Node_Str"));
        File world=new File(path);
        WorldUtil.deleteWorld(world);
        _list.removeSelectedItem();
      }
 catch (      Exception e) {
        GUIManager.getInstance().showMessage("String_Node_Str","String_Node_Str");
      }
    }
  }
);
  _loadFromList.addClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      loadSelectedWorld();
    }
  }
);
  addDisplayElement(_overlay);
  addDisplayElement(_list,"String_Node_Str");
  addDisplayElement(_loadFromList,"String_Node_Str");
  addDisplayElement(_goToBack,"String_Node_Str");
  addDisplayElement(_createNewWorld,"String_Node_Str");
  addDisplayElement(_deleteFromList,"String_Node_Str");
  update();
}

Fixed version (ground truth):
public UISelectWorldMenu(){
  maximaze();
  _overlay=new UIImageOverlay("String_Node_Str");
  _overlay.setVisible(true);
  _window=new UIDialogCreateNewWorld("String_Node_Str",new Vector2f(512f,256f));
  _window.center();
  _window.setModal(true);
  GUIManager.getInstance().addWindow(_window,"String_Node_Str");
  _list=new UIList(new Vector2f(512f,256f));
  _list.setVisible(true);
  _list.addDoubleClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      loadSelectedWorld();
    }
  }
);
  _goToBack=new UIButton(new Vector2f(256f,32f));
  _goToBack.getLabel().setText("String_Node_Str");
  _goToBack.setVisible(true);
  _loadFromList=new UIButton(new Vector2f(128f,32f));
  _loadFromList.getLabel().setText("String_Node_Str");
  _loadFromList.setVisible(true);
  _createNewWorld=new UIButton(new Vector2f(192f,32f));
  _createNewWorld.getLabel().setText("String_Node_Str");
  _createNewWorld.setVisible(true);
  _deleteFromList=new UIButton(new Vector2f(128f,32f));
  _deleteFromList.getLabel().setText("String_Node_Str");
  _deleteFromList.setVisible(true);
  _createNewWorld.addClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      GUIManager.getInstance().setFocusedWindow(_window);
    }
  }
);
  _deleteFromList.addClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      if (_list.getSelectedItem() == null) {
        GUIManager.getInstance().showMessage("String_Node_Str","String_Node_Str");
        return;
      }
      try {
        ConfigObject config=(ConfigObject)_list.getSelectedItem().getValue();
        String path=Terasology.getInstance().getWorldSavePath((String)config.get("String_Node_Str"));
        File world=new File(path);
        WorldUtil.deleteWorld(world);
        _list.removeSelectedItem();
      }
 catch (      Exception e) {
        GUIManager.getInstance().showMessage("String_Node_Str","String_Node_Str");
      }
    }
  }
);
  _loadFromList.addClickListener(new IClickListener(){
    public void clicked(    UIDisplayElement element){
      loadSelectedWorld();
    }
  }
);
  fillList();
  addDisplayElement(_overlay);
  addDisplayElement(_list,"String_Node_Str");
  addDisplayElement(_loadFromList,"String_Node_Str");
  addDisplayElement(_goToBack,"String_Node_Str");
  addDisplayElement(_createNewWorld,"String_Node_Str");
  addDisplayElement(_deleteFromList,"String_Node_Str");
  update();
}