var current_category = "ProductOverview";
	var fadein_timer;
	var fader_maxsteps = 30; // number of steps to take to change from start color to endcolor
	var fader_stepinterval = 20; // time in miliseconds of a single step
	
	function set_current_fade_value(value){
		if (value == 0){
			document.getElementById("div" + current_category).style.display = "none";
		} else {
			document.getElementById("div" + current_category).style.display = "";
		}
		document.getElementById("div" + current_category).style.opacity = value;
		document.getElementById("div" + current_category).style.MozOpacity = value;
		document.getElementById("div" + current_category).style.KhtmlOpacity = value;
		document.getElementById("div" + current_category).style.filter = "alpha(opacity=" + parseInt(Math.round(value*100)) + ")";
	}
	  
	function change_category(new_category_name){
		if (new_category_name == current_category) {return;}
		if(typeof(fadein_timer) != 'undefined'){clearTimeout(fadein_timer);}
		set_current_fade_value(0.0);
		document.getElementById("nav" + current_category).style.backgroundColor = '';
		document.getElementById("nav" + current_category).style.color = '';
		current_category = new_category_name;
		document.getElementById("nav" + current_category).style.backgroundColor = '#abcff1';
		fade_begin(1);
	}
	
	
	function fade_begin(current_step) {
		if (current_step <= fader_maxsteps) {	
			set_current_fade_value(current_step/fader_maxsteps);
			current_step++;
			fadein_timer = setTimeout("fade_begin(" + current_step + ")",fader_stepinterval);
		} else {
			clearTimeout(fadein_timer);
			set_current_fade_value(1.0);
		}   
	}