function showTab(cat) {
	tabss = document.getElementById('tabs');

	tabz = tabss.getElementsByTagName('li');

	toshow = document.getElementById('cat'+cat);
	tohide = document.getElementById('cat'+activeTabNum);

	activeLi = tabz[cat];
	nonactiveLi = tabz[activeTabNum];

	activeImg = getImg(activeLi); 
	nonactiveImg = getImg(nonactiveLi);

	toshow.className = 'one_cat';
	activeImg.src = getImgPath(cat, true);

	if(cat != activeTabNum) {
		tohide.className = 'one_cat_hidden';
		nonactiveImg.src = getImgPath(activeTabNum, false);
	}

	activeTabNum = cat;
	return false;
}

function getImg(liElem) {
	return liElem.getElementsByTagName('a')[0].getElementsByTagName('img')[0];
}

function getImgPath(num, isActive) {
	suffix = isActive ? 'on.gif' : '.gif';
	return img_dir+'cat'+(num+1)+suffix;
}