public event EventHandler OnChangeValue;
protected void drp_SelectedIndexChanged(object sender, EventArgs e)
{
if(OnChangeValue != null)
OnChangeValue(sender, e);
}
protected void Page_Load(object sender, EventArgs e)
{
ucBox.OnChangeValue += new EventHandler(ValueChanged);
}
protected void ValueChanged(object sender, EventArgs e)
{
DropDownList drp = (DropDownList)sender;
lblDisplay.Text = drp.SelectedValue.Substring(0,3);
}