Creating a readonly asp.net dropdown list custom control

Currently ASP.Net Dropdown list doesnot have a readonly property,
In some senario user may want a readonly version of Dropdownlist. In most of the cases we make it Disable.

The following code describes the Creation of a webcontol.

    [ToolboxData("<{0}:DropDownReadOnly runat=server></{0}:DropDownReadOnly>")]
    public class DropDownReadOnly : DropDownList
    {
        private bool _readOnly;
        private TextBox tb = new TextBox();
        private Image img = new Image();
        Table t = new Table();
        public bool ReadOnly
        {
            get
            {
                return _readOnly;
            }
            set
            {
                _readOnly = value;
            }
        }
        public string DropDownImgUrl
        {
            set { img.ImageUrl = value; }
        }
        protected override void Render(System.Web.UI.HtmlTextWriter writer)
        {
            if (_readOnly)
            {
                if ((System.Web.UI.WebControls.ListControl)(this) != null && ((System.Web.UI.WebControls.ListControl)(this)).SelectedItem != null)
                {
                    tb.Text = ((System.Web.UI.WebControls.ListControl)(this)).SelectedItem.Text;
                    tb.ReadOnly = true;
                    if (this.Width.Value > 24)
                        tb.Width = new Unit(this.Width.Value - 24);
                    tb.Style.Add("border", "solid 1px #7F9DB9");
                    tb.Style.Add("border-right", "0px none");
                    tb.Style.Add("height", "17px");

                    t.CellPadding = 0;
                    t.CellSpacing = 0;
                    TableCell tc = new TableCell();
                    tc.Controls.Add(tb);
                    TableCell tc2 = new TableCell();
                    tc2.Controls.Add(img);
                    TableRow tr = new TableRow();
                    tr.Cells.AddRange(new TableCell[] { tc, tc2 });
                    t.Rows.Add(tr);
                    t.RenderControl(writer);
                }
            }
            else
                base.Render(writer);
        }

Here when readonly property is set we are rendering a textbox and an image, which is dropdown arrow.


Regards,
Debata