title: cocoa: detect inactive states of all the running application
body: <p>Greetings!
  I am very new to this cocoa and I am trying to achieve something like activity monitor. i have list of all the running applications and I would like to observe these app and get notified when any app goes to [Not Responding] state like in activity monitor. Checked NSWorkSpace and NSRunningApplication but didnt got much help.</p>
  
  <p>Please enlighten me on this.</p>
  
  <p>Thanks in advance
  Ankit</p>