Why does this window subclassing code crash?

Question

I am trying to subclass the window that currently has focus. I do this by monitoring for HCBT_ACTIVATE events using a CBT hook, and set and unset the WndP

Answer 1

lpfnOldWndProc and hWndSubclass are global pointers. Seems like you've got only one per process. What if a process creates more than one window?

Then you will unsubclass only the last one.

EDIT: Also, why do you tear down in Process DETACH?