To make use of PW Core you must register to receive its runtime notifications using Mozilla's Observer service. To do this you need to know the notification's topic which is 'experimental-notify-plugin-call'. If you are new to the Mozilla Observer service, you may want to familiarize yourself with it before proceeding further. You can find more information on the Observer service [http://developer.mozilla.org/en/docs/nsIObserverService here] and [http://developer.mozilla.org/en/docs/nsIObserver here]. Below are a number of JavaScript snippets that would be useful to developers trying to work with PW Core: