/// <summary>
        /// 处理鼠标左键按下消息
        /// </summary>
        /// <param name="m">消息</param>
        protected virtual void WmLButtonDown(ref Message m)
        {
            UIControl control = this.FindUIChild(Util.GetMousePosition(m.LParam));

            this.CaptureControl = control = (control != null && control.Enabled) ? control : null;
            if (control != null)
            {
                control.WndProc(ref m);
                m.Result = NativeMethods.TRUE;
            }
        }
 /// <summary>
 /// 处理鼠标移动消息
 /// </summary>
 /// <param name="m">消息</param>
 protected virtual void WmMouseMove(ref Message m)
 {
     if ((Control.MouseButtons & MouseButtons.Left) == MouseButtons.None)//未按下左键
     {
         this.WmLButtonDown(ref m);
     }
     else//左键按下
     {
         UIControl lastAccess = this.CaptureControl;
         if (lastAccess != null)
         {
             lastAccess.WndProc(ref m);
             m.Result = NativeMethods.TRUE;
         }
     }
 }