JButton btn =  new  JButton();
        btn.setText("gggggg");
        jToolBar1.add(btn);
        Dimension dd = ((FlowLayout)(jToolBar1.getLayout())).minimumLayoutSize(jToolBar1);
        jToolBar1.setMinimumSize(dd);
        jToolBar1.setMaximumSize(dd);
        jToolBar1.setPreferredSize(dd);
        jToolBar1.invalidate();
         this .getContentPane().invalidate();

 package  JFXDCtrl;
 import  javax.swing.JButton;
 import  javax.swing.JInternalFrame;

 public   class  JMDITaskButton  extends  JButton {
     public  JInternalFrame MDIChild;
     public  JMDITaskButton(JInternalFrame obj) {
         super ();
        MDIChild = obj;
        setText(obj.getTitle());
    }   
}

 package  JFXDCtrl;

 import  java.awt.Component;
 import  java.awt.Dimension;
 import  java.awt.FlowLayout;
 import  java.awt.event.ActionEvent;
 import  java.awt.event.ActionListener;
 import  java.awt.event.ComponentEvent;
 import  java.awt.event.ComponentListener;
 import  java.awt.event.ContainerAdapter;
 import  java.beans.PropertyVetoException;
 import  javax.swing.JInternalFrame;
 import  javax.swing.JPanel;
 import  javax.swing.event.InternalFrameEvent;
 import  javax.swing.event.InternalFrameListener;

 public   class  JMDITaskBar  extends  JPanel {
     boolean  IsAnybodyHere = false;
    /** Creates a new instance of JMDITaskBar */
     public  JMDITaskBar() {
         super ();
         this .setLayout( new  FlowLayout(FlowLayout.LEFT));
         this .addComponentListener( new  ComponentListener() {
             public   void  componentHidden(ComponentEvent e) {
            }
             public   void  componentMoved(ComponentEvent e) {
            }
             public   void  componentResized(ComponentEvent e) {
                 if  (IsAnybodyHere) {
                    ReLayout();                    
                }
            }
             public   void  componentShown(ComponentEvent e) {
            }
        } );
        
         this .addContainerListener( new  ContainerAdapter() {
             public   void  componentAdded(java.awt.event.ContainerEvent evt) {
                ReLayout();
            }
             public   void  componentRemoved(java.awt.event.ContainerEvent evt) {
                ReLayout();
            }
        });
    }
    
     private   void  ReLayout() {
        doLayout();
         int  k =  0 ;
         for  ( int  i= 0 ; i<getComponentCount(); i++) {
            Component C = getComponent(i);
             int  p = C.getY() + C.getHeight() + ((FlowLayout)(getLayout())).getVgap();
             if  (k<p) k=p;
        }
         if  (k< 26 ) k= 26 ;
        setPreferredSize( new  Dimension(getWidth(),k));
        setSize( new  Dimension(getWidth(),k));
        getParent().doLayout();
    }
    
     public   void  AddInternalFrame(JInternalFrame mdiChild) {
        JMDITaskButton bt =  new  JMDITaskButton(mdiChild);
        add(bt);
        bt.addNotify();
        bt.addActionListener( new  ActionListener() {
             public   void  actionPerformed(ActionEvent e) {
                ((JMDITaskButton)(e.getSource())).MDIChild.moveToFront();
                 try  {
                    ((JMDITaskButton)(e.getSource())).MDIChild.setMaximum(true);
                }  catch  (PropertyVetoException ex) {
                    ex.printStackTrace();
                }
            }
        });
        
        mdiChild.addInternalFrameListener( new  InternalFrameListener() {
             public   void  internalFrameActivated(InternalFrameEvent e) {
            }
             public   void  internalFrameClosed(InternalFrameEvent e) {
                 for  ( int  i= 0 ; i< getComponentCount();i++) {
                    JMDITaskButton bc = (JMDITaskButton) getComponent(i);
                     if  (bc.MDIChild==e.getSource()) {
                        remove(i);
                         break ;
                    }
                }
            }
             public   void  internalFrameClosing(InternalFrameEvent e) {
            }
             public   void  internalFrameDeactivated(InternalFrameEvent e) {
            }
             public   void  internalFrameDeiconified(InternalFrameEvent e) {
            }
             public   void  internalFrameIconified(InternalFrameEvent e) {
            }
             public   void  internalFrameOpened(InternalFrameEvent e) {
            }
        });
        // I don't know what happening in netbeans designer,
        //  so I have made dirty hack :)
        IsAnybodyHere = true; 
    }    
}

             public   void  internalFrameClosed(InternalFrameEvent e) {
                 for  ( int  i= 0 ; i<getComponentCount();i++) {
                    JMDITaskButton bc = (JMDITaskButton) getComponent(i);
                     if  (bc.MDIChild.equals(e.getSource())) {
                        remove(bc);
                        bc.removeNotify();
                        validate();
                        repaint();
                         break ;
                    }
                }
            }