window.addEvent('domready',
	function() {		
	
		var isMacDisplayed = false;
		var isMathsDisplayed = false;
		var isCSDisplayed = false;
	
	
		// Actions
		$('show-mac').addEvent('click', toggleMac);
		$('show-maths').addEvent('click', toggleMaths);
		$('show-cs').addEvent('click', toggleCS);
		
		
		// ----------------------------------------------------------------------------- //

		function toggleMac() {
			isMacDisplayed = !isMacDisplayed;
			if(!isMacDisplayed)
				$(document.body).getElements('.mac-related-enabled').set({'class': 'mac-related'});
			else
				$(document.body).getElements('.mac-related').set({'class': 'mac-related-enabled'});
		}
	
		function toggleMaths() {
			isMathsDisplayed = !isMathsDisplayed;
			if(!isMathsDisplayed)
				$(document.body).getElements('.maths-related-enabled').set({'class': 'maths-related'});
			else
				$(document.body).getElements('.maths-related').set({'class': 'maths-related-enabled'});
		}
		
		function toggleCS() {
			isCSDisplayed = !isCSDisplayed;
			if(!isCSDisplayed)
				$(document.body).getElements('.cs-related-enabled').set({'class': 'cs-related'});
			else
				$(document.body).getElements('.cs-related').set({'class': 'cs-related-enabled'});
		}
	}
);