function scrollPartLeft( el )
{
    var found = false;
    var after = false;
    var prev = null;
    $(el).up().up().select('.part').each( function(part) {
        if ( !found ) {
            if ( part.visible() )
            {
                if ( prev != null ) {
                    prev.show();
                    new Effect.Highlight( prev );
                } else {
                    after = true;
                }
                found = true;
            }
            prev = part;
        } else {
            if ( !after ) {
                part.hide();
                after = true;
            }
        }
    } );
}

function scrollPartRight( el )
{
    var found = false;
    var after = false;
    var done = false;
    var first = null;
    $(el).up().up().select('.part').each( function(part) {
        if ( !found ) {
            if ( part.visible() )
            {
                first = part;
                found = true;
            }
        } else {
            if ( !after ) {
                after = true;
            } else if ( !done )
            {
                first.hide();
                part.show();
                new Effect.Highlight( part );
                done = true;
            }
        }
    } );
}