>I have a class (derived from form ) which is the base class for allmy dialogs. I set the Closable property to false so I have control over what goes on while closing the window. But the X button on the top-right most corner onthe titlebar does not get disabled. It does get disabled on regular forms derived from form class. Is there anything special that I need to do in my class?

Are you saying that any form based on this class has the "X" button disabled? Isn't this what you intended?