title: Firefox SDK : Listen for a change in non addon specific about:config entry
body: <p>I am trying to listen for changes to settings in firefox's about:config that the user could have changed while my addon is running. The settings in question are part of the browser and not created by my addon.</p>
  
  <p>I can read and set them manually when the user has used my addon with no problems using the "preferences/service" module, but I want to be able to make the appropriate changes in my addon if the user has changed a setting in about config independently of my addon.</p>
  
  <p>The "simple-prefs" module provides a listener but that is only for settings specific to your application, like "extension.myaddon.mypreference" where as the settings I need to watch are like "network.someoptionhere"</p>
  
  <p>If someone could point me in the right direction as to how I would go about this I would greatly appreciate it.</p>