title: How to get active window that is not part of my application?
body: <p>How can I get the Window Title that the user currently have focus on?
  I'm making a program that runs with another Window, and if the user does not have focus on that window I find no reason for my program to keep updating. </p>
  
  <p>So how can I determine what window the user have focus on? </p>
  
  <p>I did try to look into</p>
  
  <pre><code>[DllImport("user32.dll")]
  static extern IntPtr GetActiveWindow();
  </code></pre>
  
  <p>but I seems I can only use that if the Window is part of my application which is it not. </p>