title: JPanel with null layout in JScrollPane - don't see elements
body: <p>I want to set every element location with <code>.setLocation(x, y)</code></p>
  
  <p>I need a <code>JPanel</code> in a <code>JScrollPane</code>. But when I add components to <code>JPanel</code>, only buttons are showing. But not <code>JLabel</code>.</p>
  
  <p>Method below is calling in <code>JFrame</code> constructor:</p>
  
  <pre><code>private void initGUI_test() {
      this.setSize(950, 700);
      this.setResizable(false);
      this.getContentPane().setLayout(null);
  
      JScrollPane mainScroll = new JScrollPane(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
      JPanel container = new JPanel();
  
      mainScroll.setSize(900,500);
      mainScroll.setLocation(0,100);
      mainScroll.setBorder(BorderFactory.createLineBorder(Color.blue));
      mainScroll.add(container);
  
      container.setLayout(null);
      container.setLocation(0, 0);
      container.setSize(900, 500);
  
      JLabel rowA = new JLabel();
      rowA.setSize(180, 26);
      rowA.setLocation(10, 100);
      rowA.setText("Row A");
  
      JButton loadButton = new JButton();
      loadButton.setSize(180, 34);
      loadButton.setLocation(290, 110);
      loadButton.setText("Load file");
  
      container.add(rowA);
      container.add(loadButton);
  
      this.getContentPane().add(mainScroll);
  }
  </code></pre>