[Solved] How can I manage windows of applications opened using Win32 API (Notepad, Word, Outlook, Chrome etc.)

The answer is you cannot replace the window procedure cross-process with SetWindowLongPtr and SetClassLongPtr . Calling SetWindowLongPtr with the GWLP_WNDPROC index creates a subclass of the window class used to create the window. An application can subclass a system class, but should not subclass a window class created by another process. Calling SetClassLongPtr with the … Read more