SetWindowsHookEx returns 0 when compiling for the .NET 4.0 framework in 32bit machines

Question

I\'m trying to set a low level windows keyboard hook to grab three keys pressed even if the application is not in focus. To do this I\'m calling SetWindowsHookEx as

Answer 1

From the documentation for SetWindowsHookEx

hMod [in]
HINSTANCE
A handle to the DLL containing the hook procedure pointed to by the lpfn parameter. The hMod parameter must be set to NULL if the dwThreadId parameter specifies a thread created by the current process and if the hook procedure is within the code associated with the current process.

So you should be passing in IntPtr.Zero for NULL

//install hook
  hKeyboardHook = SetWindowsHookEx(
    WH_KEYBOARD_LL,
    KeyboardHookProcedure,
    IntPtr.Zero,
    0);