I don't think I'm alone in wondering exactly what it is you are asking. Can you be a bit more clear exactly what you're trying to do? Here is my best guess: You want some default behaviour for a message type of dialog. Eg:
And the dialog that is presented already has an OK button, and a window closing 'X' that works, etc... If this is the case, then write your own MsgBox class that extends Dialog, and use this new class, instead of Dialog. But in any event, to make use of a class, you need to instantiate it, unless of course you make some static members/methods.