title: Why JComboBox ignore PrototypeDisplayValue
body: <p>In connections with these two post @iMohammad, 
  <a href="https://stackoverflow.com/questions/8675038/increasing-decreasing-font-size-inside-textarea-using-jbutton">Increasing/Decreasing Font Size inside textArea using JButton</a> and
  <a href="https://stackoverflow.com/questions/8679088/changing-font-style-when-clicking-on-a-jbutton-java">Changing Font Style when Clicking on a JButton Java</a> ..., I'm facing with really funny issue that came from <code>JComboBox</code>by passing <code>setPrototypeDisplayValue</code> as an argument for <code>JComboBox's size</code> on the screen</p>
  
  <p>please how can I resize <code>JComboBox</code> dynamically depends of <code>Font</code>, same as works correctly for another JComponents that I tried in my <a href="http://sscce.org/" rel="nofollow noreferrer">sscce</a></p>
  
  <pre><code>import java.awt.*;
  import java.awt.event.*;
  import javax.swing.*;
  
  public class ComboBoxFontChange extends JFrame {
  
      private static final long serialVersionUID = 1L;
      private JComboBox cbox = new JComboBox();
      private JTextField tfield = new JTextField("Change");
      private JLabel label = new JLabel("Cash");
      private JButton button = new JButton("++ Font");
      private JTextField text;
      private JPanel panel = new JPanel();
  
      public ComboBoxFontChange() {
          super("Combo Box Font change");
          text = (JTextField) cbox.getEditor().getEditorComponent();
          cbox.addItem("Change");
          cbox.addItem("Cash");
          cbox.addItem("Font");
          tfield.setColumns(5);
          button.addActionListener(new ActionListener() {
  
              @Override
              public void actionPerformed(ActionEvent e) {
                  Font font = cbox.getFont();
                  font = font.deriveFont((float) (font.getSize2D() * 1.10));
                  cbox.setFont(font);
                  // EDIT
                  cbox.setPrototypeDisplayValue(cbox.getSelectedItem().toString());
                  tfield.setFont(font);
                  button.setFont(font);
                  label.setFont(font);
                  //panel.revalidate();
                  //panel.repaint();
                  pack();
              }
          });
          //panel.setLayout(new GridLayout(2, 2, 10, 10));
          panel.add(cbox);
          panel.add(label);
          panel.add(tfield);
          panel.add(button);
          setDefaultCloseOperation(EXIT_ON_CLOSE);
          add(panel);
      }
  
      public static void main(String[] args) {
          SwingUtilities.invokeLater(new Runnable() {
  
              @Override
              public void run() {
                  ComboBoxFontChange frame = new ComboBoxFontChange();
                  frame.pack();
                  frame.setVisible(true);
              }
          });
      }
  }
  </code></pre>