// show or hide a selected element
// if no state is given, the visibility is toggled
// otherwise visibility is set to hidden or visible as selected
function showHide(e, state) {
el = document.getElementById(e);
if (state == "hidden") {
el.style.visibility = "hidden";
} else if (state == "visible") {
el.style.visibility = "visible";
} else {
el.style.visibility = el.style.visibility == "visible" ? "hidden" : "visible";
}
}