function contentSwitch(icon) {
	var icons = document.getElementById('icons').getElementsByTagName('li').length;
	//switch off all tabs and content
	for (i=0; i<icons; i++){
		document.getElementById('icon' + (i+1)).style.display='none';
		document.getElementById('icon' + (i+1) + '_content').style.display='none';
	}
	
	//switch on the selected tab and content	
	document.getElementById(icon+'_content').style.display='block';
}