title: Customizing fullpage.js to skip section(s) dynamically
body: <p>The question is simple but i'm not able to make a script by myself for what i need...
  I am actually using a script ( fullpage.js ) who toggle some classes into a container ( in my case switching from fp-viewing-1 to fp-viewing-x ) when you scroll down/up between sections.
  I need to make a script that listen from this container and toggle a new class into a div ONLY when a class ( in my case fp-viewing-3 ) is added to this container ( from the fullpage.js script of course ).</p>
  
  <p>Any way to make it?</p>