title: Java JFrame is very strange
body: <p>When I am running this, JLabel is not visible, but when I resize window (with mouse) JLabel is showed. Why? </p>
  
  <pre><code>import javax.swing.*;
  import java.awt.*;
  
  public class FrmTaoLogin extends JFrame {
  
    private JPanel pnlLeft = new JPanel();
  
    public FrmTaoLogin() {
  
      super();
  
      pnlLeft.setBorder(BorderFactory.createEtchedBorder());
      pnlLeft.add(new JLabel("test1"));
      getContentPane().add(pnlLeft,BorderLayout.SOUTH);
  
      setDefaultCloseOperation(EXIT_ON_CLOSE);
      setSize(200, 200); 
  
    }
  
    public static void main(String[] args) {
  
      FrmTaoLogin FrmLogin = new FrmTaoLogin();
      FrmLogin.setVisible(true);
  
    }
  
  }
  </code></pre>