The GetWindowThreadProcessId function retrieves the identifier of the thread that created the specified window and, optionally, the identifier of the process that created the window.
DWORD GetWindowThreadProcessId(
HWND hWnd, // handle to window
LPDWORD lpdwProcessId // address of variable for process identifier
);
The return value is the identifier of the thread that created the window.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Windows Overview, Window Functions