title: Firefox extension creating different instance for two windows
body: <p>I created a Firefox extension and chrome extension. In Chrome I am using background.cs, so it will get loaded only once for all Chrome instances, so if I will write simple alert in background it will show alert box only for once.</p>
  
  <p>The same thing is not working with Firefox, it will show that alert message all the times when I will open new Firefox windows.</p>
  
  <p>Is there anything like background in Firefox?</p>