Cannot set CssClass property in inherited Label / TextBox WebControl

I have created a very simple custom control:

     [assembly: System.Web.UI.TagPrefix("CustomMultiLineTextBox", "evo")]
        public class CustomMultiLineTextBox : 
            System.Web.UI.WebControls.TextBox
        {

            public override int Rows
            {
                get
                {
                    return 5;
                }
            }

            public override System.Web.UI.WebControls.TextBoxMode TextMode
            {
                get
                {
                    return System.Web.UI.WebControls.TextBoxMode.MultiLine;
                }
            }
    public override string CssClass
            {
                get
                {
                    return "textboxStyle";
                }
                set
                {
//base.CssClass = "textboxStyle";
               开发者_开发问答     base.CssClass = value;
                }
            }
        }
        }

However, when I drop this control onto my aspx page the CssClass does not seem to be applied. The TextMode and Rows property are set correctly.

    <evo:CustomMultiLineTextBox ID="txtTrainingNeeds" runat="server">
</evo:CustomMultiLineTextBox>

Only if I add CssClass="textboxStyle" to markup will the CssClass be applied.

Any suggestions?

Thanks in advance

Since it doesn't look like you're modifying behavior, only data, I would set the properties to the values you want in the constructor instead of overriding the properties themselves.

public CustomMultiLineTextBox()
{
    Rows = 5;
    TextBoxMode = System.Web.UI.WebControls.TextBoxMode.MultiLine;
    CssClass = "textboxStyle";
}