sudo mkdir /media/compartida
sudo mount -t vboxsf compartir /media/compartida

gksudo gedit /etc/init.d/rc.local

sudo mount -t vboxsf compartir /media/compartida

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript">
 $(function(){ // document ready

           if (!!$('.sticky').offset()) { // make sure ".sticky" element exists

         var stickyTop = $('.sticky').offset().top; // returns number 

  $(window).scroll(function(){ // scroll event

  var windowTop = $(window).scrollTop(); // returns number 

  if (stickyTop < windowTop){
     $('.sticky').css({ position: 'fixed', top: 0 });
  } else {
     $('.sticky').css('position','static');
  }

          });

        }

     });
</script>

<div class="sticky">

///// Lo que quieres Fijar

</div>

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript">
 $(function(){ // document ready

   if (!!$('.sticky').offset()) { // make sure ".sticky" element exists

  var stickyTop = $('.sticky').offset().top; // returns number 

  $(window).scroll(function(){ // scroll event

  var windowTop = $(window).scrollTop(); // returns number 

  if (stickyTop < windowTop){
      $('.sticky').css({ position: 'fixed', top: 0 });
  }else {
      $('.sticky').css('position','static');
  }
 });

 }

     });
</script>

warning :  (/build/buildd/cairo-dock-3.3.2/src/gldit/cairo-dock-module-manager.c:gldi_module_new_from_so_file:197) this module ('/usr/lib/x86_64-linux-gnu/cairo-dock/libcd-Folders.so') was compiled with Cairo-Dock v3.3.1, but Cairo-Dock is in v3.3.2

sudo add-apt-repository ppa:cairo-dock-team/ppa  
sudo apt-get update 
sudo apt-get dist-upgrade