code: private JPanel buildHeader(JLabel label, JToolBar bar) {
          gradientPanel = new GradientPanel(new BorderLayout(), getHeaderBackground());
          label.setOpaque(false);
  
          gradientPanel.add(label, BorderLayout.WEST);
          gradientPanel.setBorder(BorderFactory.createEmptyBorder(3, 4, 3, 1));
  
          headerPanel = new JPanel(new BorderLayout());
          headerPanel.add(gradientPanel, BorderLayout.CENTER);
          setToolBar(bar);
          headerPanel.setBorder(new RaisedHeaderBorder());
          headerPanel.setOpaque(false);
          return headerPanel;
      }
docs: Creates and answers the header panel, that consists of: an icon, a title
  label, a tool bar, and a gradient background.
  
  @param label
  the label to paint the icon and text
  @param bar
  the panel's tool bar
  @return the panel's built header area