function toggleDisplay( aId, dflt ) {
    var el = document.getElementById( aId );
    var isDisplayed = ( el.style.display == dflt );
    el.style.display = ( isDisplayed ? "none" : dflt );
}

function hide( aId ) {
    var el = document.getElementById( aId );
    el.style.display = "none";
}

function show( aId, dflt ) {
    var el = document.getElementById( aId );
    el.style.display = dflt;
}