window.addEvent('domready', function() {

   codeblocks = $$('div.highlight');
   codeblocks.each(addExpander);

 });
 
 function addExpander(div){
   new Element('span',{
 		html: 'expand »',
 		'class': 'pre_expander',
     'events': {
       'click': function(){

         toggleExpander(this);

       }
     }
 	}).inject(div, 'top');
 }

 function toggleExpander(expander){

   var html = '';

   var expanderPos = expander.getPosition().y;

   if($('main').toggleClass('expanded').hasClass('expanded'))

     html = '« contract';

   else

     html = 'expand »';
   $$('div.highlight span.pre_expander').each(function(span){

       span.set('html',html);

   });

   fixScroll(expander, expanderPos);
 }
 function fixScroll(el, position){
   pos = el.getPosition().y - position;
   window.scrollTo(window.getScroll().x ,window.getScroll().y + pos);

 }
 function enableCompressedLayout(codeblocks){
   if(!codeblocks.length) return;
   new Element('span',{
 		html: 'Collapse layout',
 		'id': 'collapser',
     'events': {
       'click': function(){
         if($('page').toggleClass('collapsed').hasClass('collapsed'))
           this.set('html','Expand layout');
         else
           this.set('html','Collapse layout');
       }
     }
 	}).inject($('main'), 'top');

 }