function toggle_check_box() {
	var obj = document.getElementById('checkbox');
	var hiddenfield = document.getElementById('hiddenfield');
	if (obj.src.indexOf("/chkboxjs/true.jpg") >= 0) {
		obj.src = "/chkboxjs/false.jpg";
		hiddenfield.value = "";
	} else {
		obj.src = "/chkboxjs/true.jpg";
		hiddenfield.value = "true";
	}
	return true;
}