Catching a change in Application

Is there a way for me to catch that my application is no longer the active application?

Code:

---

Declare Function GetActiveWindow Lib "user32" Alias "GetActiveWindow" () As Long

 If GetActiveWindow <> Form1.hWnd then
 'what happens if your application isn't the active one
 end if

---

\
you can change the form1 to whatever form is your main form

Make sure you place that code in a Timer, otherwsie the code with not execute.

You can also subclass the form to detect when your form has lost focus, take a look at this post for an example.