Panel More 箭头

  protected void ImageButtonRemark_Click(object sender, ImageClickEventArgs e)
    {
        Panel PanelMark = (Panel)FormView1.FindControl("PanelMark");
        if (PanelMark != null)
        {
            PanelMark.Visible = !PanelMark.Visible;
            ImageButton btnMore = (ImageButton)sender;
            if (PanelMark.Visible && btnMore != null)
            {
                //ImageButton btnMore=(ImageButton)FormView_Detail.FindControl("ImageButtonMore");

                btnMore.ImageUrl = "~/images/collapse.jpg";
            }
            else
                btnMore.ImageUrl = "~/images/expand.jpg";
          
        }

    }