Should we add unsubclass code during dialog destruction?

Question

What will happen when we subclass a windows dialog and dialog is closed?

Scenario is that I am subclassing a dialog and application can launch many instances of that dialog.

Is it necessary to add unsubclassing code to all the dialogs in thier destruction logic.

I think when dialogs get closed there is no need to unsubclass them because dialogs already destroyed.

Answer 1

Assuming you're talking straight Win32 API, then yes. Though be aware that if you've any resources you're managing manually, you must have tidied them up in the WM_CLOSE message.

Answer 2

If you're using instance subclassing (SetWindowLongPtr), then since when the window gets torn down it doesn't matter which WndProc it's using--it's about to vanish anyway.

If you're using global subclassing (SetClassLongPtr) then it would probably be a good idea to remove the subclass once the last subclassed window is closed (i.e. not per window) so that any future windows created with that class don't get subclassed--unless that's what you want, of course.