// paste getElementsByClass function (see above) here
function getElementsByClass( searchClass, domNode, tagName) {
	if (domNode == null) domNode = document;
	if (tagName == null) tagName = '*';
	var el = new Array();
	var tags = domNode.getElementsByTagName(tagName);
	var tcl = " "+searchClass+" ";
	for(i=0,j=0; i<tags.length; i++) {
		var test = " " + tags[i].className + " ";
		if (test.indexOf(tcl) != -1)
			el[j++] = tags[i];
	}
	return el;
}
 
function showtab(tabname,elem,div_cont) 
{
	// hide every element with class 'tab' 
	var tabs = getElementsByClass('tab');
	var items = getElementsByClass('m');
	
	for(i=0; i<tabs.length; i++){
		tabs[i].style.display = 'none';
		if(i==0)
		items[i].style.background = "url(images/btn_m1.gif) no-repeat right top";
		else if(i==1)
		items[i].style.background = "url(images/btn_m2.gif) no-repeat right top";
		else if(i==2)
		items[i].style.background = "url(images/btn_m3.gif) no-repeat right top";
	}
	// hide every element with class 'tab'		

	document.getElementById(tabname).style.display='block';
	document.getElementById(elem).style.background = "url(images/btn_" + elem + "_on.gif) no-repeat right top";
	 // show element with given tabname
	if (div_cont == 'adv_1') {
		document.getElementById('adv_c').style.background = "url(" + adv_1.src + ") no-repeat";
	}	
	if (div_cont == 'adv_2') {
		document.getElementById('adv_c').style.background = "url(" + adv_2.src + ") no-repeat";
	}
	if (div_cont == 'adv_3') {
		document.getElementById('adv_c').style.background = "url(" + adv_3.src + ") no-repeat";
	}
}

function showMainTab(selected_tab) {
	
	document.getElementById('main_content_1').style.display = 'none';
	document.getElementById('main_content_2').style.display = 'none';
	document.getElementById('main_content_3').style.display = 'none';

if (selected_tab == 'main_content_1') {
		document.getElementById('main_content_1').style.display = 'block';
	}	
	if (selected_tab == 'main_content_2') {
		document.getElementById('main_content_2').style.display = 'block';
	}
	if (selected_tab == 'main_content_3') {
		document.getElementById('main_content_3').style.display = 'block';
	}
}