// 下拉按钮的点击事件
        private void but_Click(object sender, EventArgs e)
        {
            Button but = (Button)sender;
            int    x   = ControlsUtils.LocationOnClient(this.拉按钮_pan).X;

            if (this.button1.Name.Equals(but.Name))
            {
                if (historicalPanel == null || historicalPanel.IsDisposed)
                {
                    historicalPanel = ControlsUtils.GetHistoricalPanel(拉按钮_but
                                                                       , 拉按钮_pan.Parent.FindForm().Controls
                                                                       , false
                                                                       , history
                                                                       , 拉按钮_but.Width + this.button1.Width, 23);
                    historicalPanel.Location = new Point(x, 拉按钮_pan.Location.Y + 拉按钮_pan.Height + 5);
                }
                else
                {
                    historicalPanel.Dispose();
                    historicalPanel = null;
                }
            }
        }