绝对是代码有问题嘛！

不介意的话把你代码发我瞧瞧。lw@szcyt.cn

 private void panel1_DragEnter(object sender, DragEventArgs e)
        {
            e.Effect = DragDropEffects.Link  ;
        }
        public DrawRectangle rectangle;
        private void panel1_DragDrop(object sender, DragEventArgs e)
        {
            string itemtype = e.Data.GetData(typeof(string)).ToString();
            if (itemtype == "A")
            {

                
                Point lefttoppoint = this.PointToScreen(this.panel1.Location);
                DrawRectangle objrect = new DrawRectangle(e.X - lefttoppoint.X, e.Y - lefttoppoint.Y, 100, 50);
                //objrect.intStatusTypeId = 0;
                //objrect.dblStatusId = 1;
                objrect.strStatusName = "状态1 ";
                rectangle  = objrect;
             
                repaint();
               
    
            }
         
        }

        private void toolStripButton1_MouseDown_1(object sender, MouseEventArgs e)
        {
            toolStrip1.DoDragDrop("A", DragDropEffects.Link   );
        }

      

       
        public void drawMouseObjs(MouseEventArgs e, int intEvent)
        {


            DrawRectangle objrect = rectangle;
            switch (intEvent)
            {
                case 1://mouseDown() 
                    if ( objrect.contains(e.X, e.Y))//按下的鼠标坐标在节点的范围内。 
                    {
                        Graphics g =panel1 . CreateGraphics();
                        objrect.last_x =  objrect._x - e.X;
                        objrect.last_y =  objrect._y - e.Y;
                         objrect.isMove = 1;
                        int x1 =  objrect._x;
                        int y1 =  objrect._y;
                        int w1 =  objrect._w;
                        int h1 =  objrect._h;
                        //Pen penWhite = new Pen(Color.White, 2);
                        //  g.DrawRectangle(penWhite, x1, y1, w1, h1);
                        //g.FillRectangle(new SolidBrush(Color.White), x1, y1, w1, h1);
                       // g.FillRectangle(new SolidBrush(Color.White), x1 + 6, y1 + 6, w1, h1);   //用白色擦掉画好的节点         
                        //g.DrawRectangle(new Pen(Color.Black), x1, y1, w1, h1);//给节点加个黑边框。代表选中了该节点，可以拖动了。         
                        g.Dispose();
                        return;
                    }
                    break;

                case 2://mouseMove() 
                    if ( objrect.isMove == 1)
                    {
                        Graphics g = panel1.CreateGraphics();
                        int x1 =  objrect._x;
                        int y1 =  objrect._y;
                        int w1 =  objrect._w;
                        int h1 =  objrect._h;
                        //g.DrawRectangle(new Pen(Color.White), x1, y1, w1, h1);    
                        //用白色擦掉拖动时上一位置的节点      
                         g.FillRectangle(new SolidBrush(Color.White), 0, 0, this.Width, this.Height);
                         //g.Clear(panel1.BackColor);
                         objrect.setLocation(e.X, e.Y);
                         //int x2 = objrect._x;
                         //int y2 = objrect._y;
                         //Pen penBlack = new Pen(Color.Black);
                         //g.DrawRectangle(penBlack, x2, y2, w1, h1);  //在新位置画新的带黑边框的节点 
                         repaint();
                        g.Dispose();
                        return;

                    }
                    break;
                case 3://mouseUp() 
                    if ( objrect.isMove == 1)
                    {
                        updateLocation(e,  objrect);//更新节点位置 
                         objrect.isMove = 0;
                        //repaint();//在新位置处，重新画一个带颜色和阴影及节点说明的矩形框。 
                        return;
                    }
                    break;
            } 

        }

        public void updateLocation(MouseEventArgs e,DrawRectangle  objrect)
        {

             objrect.setLocation(e.X, e.Y);
            //this.checkStatus( objrect);//节点是否在画板内，省略 
            int PosX =  objrect._x + Convert.ToInt32( objrect._w / 2);
            int PosY =  objrect._y + Convert.ToInt32( objrect._h / 2);
            double dblStatusId =  objrect.dblStatusId;

        }
 
        public void repaint()//画图 
        {
            
                Graphics g = panel1.CreateGraphics();
                //先将图形所有区域用白色填充                                 

                Pen WhitePen = new Pen(Color.White);
                //g.DrawRectangle(WhitePen, 0, 0, this.Width, this.Height);
                //g.FillRectangle(new SolidBrush(Color.White), 0, 0, this.Width, this.Height);
                //填充完毕 
                DrawRectangle rect = rectangle;

                int intType = rect.intStatusTypeId;
                string strType = " ";
                switch (intType)
                {
                    case 0:
                        strType = "开始 ";
                        break;
                    case 1:
                        strType = "结束 ";
                        break;
                    case 2:
                        strType = "普通 ";
                        break;
                    case 3:
                        strType = "子流 ";
                        break;
                    case 4:
                        strType = "自动 ";
                        break;
                    case 5:
                        strType = "分流 ";
                        break;
                    case 6:
                        strType = "合流 ";
                        break;
                    case 7:
                        strType = "转流程 ";
                        break;
                }

                int x1 = rect._x;
                int y1 = rect._y;
                int w1 = rect._w;
                int h1 = rect._h;
                string strName = rect.strStatusName;//节点名称 

                g.FillRectangle(new SolidBrush(Color.Orange), x1, y1, w1, Convert.ToInt32(h1 * 0.6));//用颜色填充上半部分，用来说明节点的类型 
                g.FillRectangle(new SolidBrush(Color.Blue), x1, y1 + Convert.ToInt32((h1 * 0.6)), w1, Convert.ToInt32(h1 * 0.4));//用颜色画下半部分，用来说明是第几个节点。 
                Font drawFont = new Font("宋体 ", 9);
                StringFormat drawFormat = new StringFormat();

                drawFormat.Alignment = StringAlignment.Center;
                SolidBrush drawBrush = new SolidBrush(Color.Black);

                RectangleF drawRect = new RectangleF(x1, y1, w1, Convert.ToInt32(h1 * 0.6));
                RectangleF drawRect2 = new RectangleF(x1, y1 + Convert.ToInt32(h1 * 0.6), w1, Convert.ToInt32(h1 * 0.4));
                g.DrawString(strType, drawFont, drawBrush, drawRect, drawFormat);//在上半部分添加节点类型说明文字                         
                g.DrawString(strName, drawFont, new SolidBrush(Color.White), drawRect2, drawFormat);//在下半部分添加节点编号。 
  
                g.Dispose();//释放graphics对象。 
            
        }

        private void panel1_MouseDown(object sender, MouseEventArgs e)
        {

            int intClickCount = e.Clicks;//鼠标的点击次数 
            if (e.Button == MouseButtons.Left)//左键，有对右键和双击的处理，此处省略 
            {
                if (intClickCount == 1)
                {
                    this.drawMouseObjs(e, 1);
                }
            }
        }

        private void panel1_MouseMove(object sender, MouseEventArgs e)
        {

            if (e.Button == MouseButtons.Left)
            {
                this.drawMouseObjs(e, 2);

            } 
        }
     
        private void panel1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                this.drawMouseObjs(e, 3);
            }         
        } 
       
        
    }

这是网上找的 你们看看问什么会那样