private JPanel buildUseExistingConfigurationPanel()

in src/main/java/org/apache/log4j/chainsaw/ReceiverConfigurationPanel.java [500:566]
55 lines of code
3 McCabe index (conditional complexity)

    private JPanel buildUseExistingConfigurationPanel() {
        existingConfigurationComboBoxModel = new DefaultComboBoxModel<>();

        existingConfigurationComboBox = new JComboBox<>(existingConfigurationComboBoxModel);
        existingConfigurationComboBox.setOpaque(false);
        existingConfigurationComboBox.setToolTipText("Previously loaded configurations can be chosen here");
        existingConfigurationComboBox.setEditable(true);

        existingConfigurationComboBox.getEditor().getEditorComponent().addFocusListener(
            new FocusListener() {
                public void focusGained(FocusEvent e) {
                    selectAll();
                }

                private void selectAll() {
                    existingConfigurationComboBox.getEditor().selectAll();
                }

                public void focusLost(FocusEvent e) {
                }
            });

        browseForAnExistingConfigurationButton = new JButton(new AbstractAction(" Open File... ") {
            public void actionPerformed(ActionEvent e) {
                try {

                    URL url = browseConfig();

                    if (url != null) {
                        existingConfigurationComboBoxModel.addElement(url.toExternalForm());
                        existingConfigurationComboBox.getModel().setSelectedItem(
                            url);
                    }
                } catch (Exception ex) {
                    logger.error(
                        "Error browsing for Configuration file", ex);
                }
            }
        });

        browseForAnExistingConfigurationButton.setToolTipText(
            "Shows a File Open dialog to allow you to find a configuration file");
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 0;
        c.gridwidth = 2;
        c.anchor = GridBagConstraints.LINE_START;
        c.insets = new Insets(0, 0, 5, 0);
        panel.add(browseForAnExistingConfigurationButton, c);

        c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 1;
        c.insets = new Insets(0, 5, 0, 5);
        panel.add(new JLabel(" Configuration file URL "), c);

        c = new GridBagConstraints();
        c.gridx = 1;
        c.gridy = 1;
        c.weightx = 0.5;
        c.fill = GridBagConstraints.HORIZONTAL;
        panel.add(existingConfigurationComboBox, c);


        return panel;
    }