if (document.images) {
		// preload images..
		var img0 = new Image();
		img0.src = 'http://scienceenpartage.com/images/gray_circle_tl.gif';
		var img1 = new Image();
		img1.src = 'http://scienceenpartage.com/images/gray_circle_tr.gif';
		var img2 = new Image();
		img2.src = 'http://scienceenpartage.com/images/gray_circle_bl.gif';
		var img3 = new Image();
		img3.src = 'http://scienceenpartage.com/images/gray_circle_br.gif';
	}
	
	// checking for browser..
	var ie6 = (document.getElementById) ? true : false;
	var ie5 = (document.all) ? true : false;
	
	if (ie6 || ie5) {
		var proper_browser = true;
	}
	
	// function for hovering the navigation bar via buttons
	function make_hover(id, color) {
		// checking proper browser
		if (proper_browser) {
			prefix = (ie6) ? (document.getElementById(id)) : (document.all(id));
			if (color != '') {
				prefix.style.color = color;
			} else {
				prefix.style.color = '';
				prefix.className = 'nav';
			}
		}
	}
	
	function table_hover(table, image_prefix, color, text_color) {
		// checking proper browser
		if (proper_browser) {
			prefix1 = (ie6) ? (document.getElementById(table)) : (document.all(table));
			prefix2 = (ie6) ? (document.getElementById(table + '_text')) : (document.all(table + '_text'));
			prefix1.style.backgroundColor = color;
			prefix2.style.color = text_color;
			// replace images
			document.images[table + '_circle_tl'].src = 'http://scienceenpartage.com/images/' + image_prefix + '_circle_tl.gif';
			document.images[table + '_circle_tr'].src = 'http://scienceenpartage.com/images/' + image_prefix + '_circle_tr.gif';
			document.images[table + '_circle_bl'].src = 'http://scienceenpartage.com/images/' + image_prefix + '_circle_bl.gif';
			document.images[table + '_circle_br'].src = 'http://scienceenpartage.com/images/' + image_prefix + '_circle_br.gif';
		}
	}