java swing组件上绘制直线同时添加组件后 的显示问题

Question

说明：运行后，面板上自动画出14条直线，点击“添加”按钮，生成可以拖动的JTextField控件。问题（1）面板的背景色不显示，（2）拖动JTextField控件时有残影，（3）改变JFrame大小后，残影消失，但是只能显示JTextField控件的一部分。哪位高手指点下。

 import java.awt.*;
import java.awt.event.*;
import java.awt.Graphics;
import static java.awt.BorderLayout.*;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.SwingUtilities;
import javax.swing.plaf.ButtonUI;
import javax.swing.event.*;
class Win extends JFrame 
{   
    JButton jb1,jb2,jb3,jb4,jb5;//编辑、添加、修改、删除、调度
    JButton jb6,jb7,jb8,jb9,jb10;//调试用按钮
    JPanel jp_button;//放置按钮的面板
    MyPanel jp_xianlu;//放置线路图的面板

    public static void main(String args[])
   { 
            SwingUtilities.invokeLater(new Runnable() {

                  @Override
                  public void run() {
                    Win win=new Win();
                    //win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    win.setLocationRelativeTo(null);
                    win.setVisible(true);
                  }
            });
   }

    Win()
    { 
      super("我的面板");
      setExtendedState( Frame.MAXIMIZED_BOTH );
      setLayout(new BorderLayout(30,5));

      jp_button =new JPanel();
      jp_button.setVisible(true);
      jp_button.setOpaque(true);
          jp_button.setBackground(Color.BLUE);
      add(jp_button,SOUTH);

      jp_xianlu =new MyPanel();
      add(jp_xianlu,CENTER);

//添加5个按钮并添加到面板jp_button上      
      jb1 = new JButton("编辑");
      jb2 = new JButton("添加");
      jb3 = new JButton("修改");
      jb4 = new JButton("删除");
      jb5 = new JButton("调度");
      jp_button.add(jb1);
      jp_button.add(jb2);
      jp_button.add(jb3);
      jp_button.add(jb4);
      jp_button.add(jb5);

      //Frame上添加windows监听，使之关闭按钮可用      
      addWindowListener(new WindowAdapter(){   
           public void windowClosing(WindowEvent e){ 
                System.exit(0);
           }
       });
      //点击“添加”按钮时在jp_xianlu面板上生成JLabel
         jb2.addActionListener(new ActionListener()
         {
              public void actionPerformed(ActionEvent e) {
                                setMyText(200,200);
              }
            });
     }

    //自定的可以生成LTextField的方法
    public void setMyText(int a,int b){

            MyTextField mtf= new MyTextField(); //输入标签显示内容
        mtf.setBounds(a,b,55,20);
        jp_xianlu.add(mtf);
    }   
}

//自定义监听器类：转换坐标并实现自由拖动
class MyTextField extends JTextField implements MouseListener,MouseMotionListener {  
        /** 坐标点 */  
        Point point = new Point(0, 0);  
        MyTextField(){
             super("0000000");
             addMouseListener(this);
             addMouseMotionListener(this);  
             setOpaque(true); //组件背景透明
                     setBackground(Color.RED);
        }
        /** 
         * 当鼠标拖动时触发该事件记录下鼠标按下(开始拖动)的位置（摘自苏小喵） 
         */ 
        public void mouseDragged(MouseEvent e) {  
             //转换坐标系统  
            Point newPoint = SwingUtilities.convertPoint(this, e.getPoint(), this.getParent());  
             //设置标签的新位置  
            this.setLocation(this.getX()  
                    + (newPoint.x - point.x), this.getY()  
                    + (newPoint.y - point.y));  
             //更改坐标点  
            point = newPoint;  
        } 
        public void mouseMoved(MouseEvent e){} 

        /** 
         * 当鼠标按下时触发该事件。 记录下鼠标按下(开始拖动)的位置。 
         */  
        public void mouseClicked(MouseEvent e) {}
        public void mouseEntered(MouseEvent e){}
        public void mouseExited(MouseEvent e){}
        public void mousePressed(MouseEvent e) {  
             //得到当前坐标点  
            point = SwingUtilities.convertPoint(this, e.getPoint(),  
                    this.getParent());  
        }  
        public void mouseReleased(MouseEvent e){}
    } 

//自定义面板，在其上实画线(未实现，不可用)
class MyPanel extends JPanel{
      public MyPanel(){
                setBackground(Color.GREEN);
              setOpaque(true);
                setLayout(null);
                setVisible(true);

        }
        @Override
//画14条直线        
      public void paint(Graphics g){
                g.drawLine(10,50,1900,50);
                g.drawLine(10,115,1900,115);
                g.drawLine(10,180,1900,180);
                g.drawLine(10,245,1900,245);
                g.drawLine(10,310,1900,310);
                g.drawLine(10,375,1900,375);
                g.drawLine(10,440,1900,440);
                g.drawLine(10,505,1900,505);
                g.drawLine(10,570,1900,570);
                g.drawLine(10,635,1900,635);
                g.drawLine(10,700,1900,700);
                g.drawLine(10,765,1900,765);
                g.drawLine(10,830,1900,830);
                g.drawLine(10,895,1900,895);
                    }
    }