title: How to disable an eventListener in RCP?
body: <p>I've an EventListener dedicated to listen to the focusLost() event of a Text in my view  in Eclipse RCP. The Listener's working fine. But at some point of the execution I want to disable this Listener from Listening to the Text and Later I wish it to be activated.
  How can it be deactivated or activated as per our needs programatically ?</p>