The user-defined control uses innerdefaultproperty to prompt "text content cannot be included"

I want to make a property value stored between the identifiers, like many server-side controls.

<Kvw: adctl id = "adctl1" runat = "server">
My advertisement content
</Kvw: adctl>

I do not know how to express it. The hyperlink control of the anti-encoding system found that
Persistencemode (persistencemode. innerdefaultproperty) [persistencemode (persistencemode. innerdefaultproperty), description ("hyperlink_text")]
Public Virtual string text
{
Get
{
//
}
Set
{
//
}
}

The control is successfully generated based on the gourd painting scheme and put it on the page for trial. The property value is as expected to go between labels, but when you return to the design interface, a prompt is displayed.
Cannot contain text content "...."

After careful comparison, the original class also has a limit of parsechildren (false ). In terms of words, that is to say, the control between them is not explained. Try to put a table in it. The value of text is empty. No wonder the hyperlink control overwrites the addparsedsubobject method protected override void addparsedsubobject (Object OBJ)
{
If (this. hascontrols ())
{
Base. addparsedsubobject (OBJ );
}
Else if (obj is literalcontrol)
{
This. Text = (literalcontrol) OBJ). text;
}
Else
{
String text = This. text;
If (text. length! = 0)
{
This. Text = string. empty;
Base. addparsedsubobject (New literalcontrol (text ));
}
Base. addparsedsubobject (OBJ );
}
}