how to use Built in class as Control or Window ?

[Sopan]

Hi,

I have class and I want use this class as control or windows, so how to use it?

Example :  I have a class
 Telerik.Windows.Controls.RichTextBoxUI.Dialogs.RadRichTextBoxWindow
  Now I want use this class as my control.

  I have seen demo, where already added, when I an trying to add, I get confused, whether it add as control or window.

  So whats the procedure to add it as control.

Thanks

Sopan Vaidya