//Main-Class;

public void actionPerformed(ActionEvent e){
      
      if (e.getSource() == mainMenuButtons[0]) {
         
         try {
            GameWindow.gw.setLoadingPanel();
         } catch (IOException e2) {
            e2.printStackTrace();
         }
         
         PictureIds.setObjectPictureIds();
         PictureIds.setTerrainPictureIds();
         
         try {
            GameWindow.gw.setGamePanel();
         } catch (IOException e1) {
            e1.printStackTrace();
         }


//Game-Window-class

   public void setLoadingPanel() throws IOException{
      GameWindow.this.getContentPane().removeAll();
      lpanel = new LoadingPanel();
      this.add(lpanel);
      this.validate();
      this.repaint();
      lpanel.grabFocus();
      lpanel.repaint();
   }


//LoadingPanel-class

   public LoadingPanel() {
      super();
      this.setFocusable(true);
      this.grabFocus();
      System.out.println("Loading Const.");
   }
   
   public void paint(Graphics g) {
      super.paint(g);
      System.out.println("Loading");
      g.drawImage(loadingScreen, 0, 0, null);
      g.dispose();
   }
}

//GamePanel-class
   public GamePanel() throws IOException {
      super();
      moveThread = new MoveThread(this);
      Thread start = new Thread(moveThread);
      start.start();
........
}