function flipMultiple(ip) {
		var sl = ip;

		while ((sl = sl.nextSibling).nodeType == 3);

		if (ip.value == '+') {
			sl.selectedIndex = sl.selectedIndex;
			sl.multiple = 'multiple';
			sl.size = '8';
			ip.value = '-';
			ip.title = "Close select-box for single-selection";
		}
		else {
			sl.selectedIndex = sl.selectedIndex;
			sl.multiple = '';
			sl.size = '1';
			ip.value = '+';
			ip.title = "Open select-box for multiple-selection";
		}

		ip.blur();
		ip.form.submit();
	}

	function flipIntro(txt) {
		var h1 = document.getElementById(txt);

		if (h1.className.match(/hide/))
			h1.className = 'show';
		else if (h1.className.match(/show/))
			h1.className = 'hide';
	}

	function detectChanges() {
		return false;
	}

	function detectVoid() {
		var choosen = 0;
		var probed = 0;

		/* parameters */
		var parms = document.getElementById('parameters');
		var rslts = document.getElementById('results');
		var chkbx = parms.getElementsByTagName('input');

		var len = chkbx.length;
		/* search for all tables */
		for (var l = 0; l < len; l++) {
			var cbox = chkbx.item(l);
			if (cbox.type == 'checkbox') {
				/* no files choosen
				 * input type="checkbox" id="choosen[]"
				 */
				if (cbox.name.match(/choosen/)) {
					choosen += cbox.checked ? 1 : 0;
				}

				/* no compressors choosen
				 * input type="checkbox" name="probed[]"
				 */
				if (cbox.name.match(/probed/)) {
					probed += cbox.checked ? 1 : 0;
				}
			}
		}

		if (!choosen) {
			alert('You have no files selected, the result will be void!');
			rslts.style.display = 'none';
			return false;
		}

		if (!probed) {
			alert('You have no compressor selected, the result will be void!');
			rslts.style.display = 'none';
			return false;
		}

		rslts.style.display = '';
		return true;
	}