WebComponents lists the components that generate content for the Web form. Each of these components supports the IWebContent interface, and some can contain their own list of Web items that help them generate their content.  

The type of items that can be added to the WebComponents list are restricted by the protected CanAddClass method. Descendant classes override this method to indicate what types of items can be added to the list. For example, TQueryForm limits the list to components that display or manipulate named values (TQueryButtons, TQueryFields) or layout groups that manage the layout of those items (TLayoutGroup). 

At design time, add components to the WebComponents property by bringing up the Web page editor for the containing TInetXPageProducer component. Select the TWebForm descendant in the editor, and use the editor to add child controls. 

IWebContent 

TInetXPageProducer 

CanAddClass