I also created a form class which inherits the
System.UI.Web.HtmlControls.HtmlForm and register
it as user control and use it to replace the regular <form runat=server> in
web form, every thing works
fine, but only the design view doesn't wotk in VS 2008. below are the sample
code, is it possible to solve
this issue?

namespace myControls
{
public class myForm : System.UI.Web.HtmlControls.HtmlForm
{
portected override void
RenderAttributes(System.Web.UI.HtmlTextWriter writer)
{
//...................................
}
}
}