防止其他服务器控件作为自定义ASP.NET控件的子级

Panel

<my:SpecialPanel ID=\"SpecialPanel1\" runat=\"server\">
    <!-- Allow valid HTML -->
    <input id=\"tbEmailAddress\" type=\"text\" />
</my:SpecialPanel>

SpecialPanel

<my:SpecialPanel ID=\"SpecialPanel1\" runat=\"server\">
    <!-- WRONG - Throw an Exception -->
    <asp:TextBox ID=\"tbEmailAddress\" runat=\"server\" />
</my:SpecialPanel>

public class SpecialPanel : Control
{
   protected override void AddParsedSubObject(Object obj) 
   {
      if (obj is Control) 
      {
         throw new InvalidOperationException(
             \"The \'SpecialPanel\' control cannot contain server controls\");
      }
   }
}