Adding a button to a JInternalFrame titlebar

Question

hi ,
i was looking for a way to add an additional button to the titlbar of my JInternalFrame , i found some very useful codes here but i still got a little problem , after i added the new button the title of my JInternalFrame becomes "..."
i would like to hear any suggestion you guys have ,
here is my code :
import javax.swing.*;
import javax.swing.plaf.basic.BasicInternalFrameUI;
import javax.swing.plaf.metal.MetalInternalFrameTitlePane;
import java.awt.*;
public class InternalFrameTest extends JFrame{
    public InternalFrameTest() {
        super();
        JInternalFrame jInternalFrame = new JInternalFrame("InternalFrameTest",true,true,true,true);
        myTitleBar(jInternalFrame);
        jInternalFrame.setSize(400,400);
        jInternalFrame.setVisible(true);
        JDesktopPane desktop = new JDesktopPane();
        desktop.add(jInternalFrame);
        getContentPane().add(desktop);
        setSize(500, 500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
    private void myTitleBar(JInternalFrame internalFrame){
        BasicInternalFrameUI basicInternalFrameUI = (BasicInternalFrameUI)internalFrame.getUI();
        MetalInternalFrameTitlePane northPane = (MetalInternalFrameTitlePane)basicInternalFrameUI.getNorthPane();
        JButton iconifyButton = null;
        JButton maximizeButton = null;
        JButton closeButton = null;
        Component[] components = northPane.getComponents();
        for( int i=0; i < components.length; i++ ){
            if( components[i] instanceof JButton ){
                if( i == 0 ){
                     iconifyButton= (JButton)components;
}else if( i == 1 ){
maximizeButton= (JButton)components[i];
}else{
closeButton= (JButton)components[i];
northPane.remove( components[i] );
//create the additional button
JButton additionalButton = new JButton("+");
additionalButton.setFont(new Font("Arial",Font.BOLD,9));
additionalButton.setPreferredSize(new Dimension(14,14));
additionalButton.setMargin(new Insets(0, 0, 0, 0));
//create a new buttons panel
JPanel buttonsPanel = new JPanel();
buttonsPanel.setOpaque(false);
buttonsPanel.setMaximumSize(new Dimension(-1, 14));
//adding the buttons to the buttons panel
buttonsPanel.add(additionalButton);
buttonsPanel.add(iconifyButton);
buttonsPanel.add(maximizeButton);
buttonsPanel.add(closeButton);
//adding the panel to the north pane of the internal frame
northPane.setLayout(new BorderLayout());
northPane.add(buttonsPanel,BorderLayout.EAST);
public static void main(String[] args) {
new InternalFrameTest();
thanks in advance ,
oz

Answer 1

In general, it is very bad practice to access internal structures of UI delegates. Every time you find yourself casting getUI() result to a specific class and accessing the internal components, you are digging a very nasty hole. In this case, just adding the button is not enough - the internal frame title pane has a custom layout manager that knows nothing about it.
You will have to dig much deeper and create your own UI delegate for internal frames to handle all the cases (including theme support, rollover effects, layout and RTL). Another option is to use Substance LAF that provides an API to add custom buttons to title panes [1]. This example shows how to do this for top-level frames, but the same would work for internal frames as well.
[1] https://substance.dev.java.net/docs/api/SetRootPaneCustomTitleButtons.html