function view_element(element)
{
    return !(document.getElementById(element)
           &&
           ( document.getElementById(element).style.display == 'none'
           ||
            document.getElementById(element).style.display == ''));
}

function display_element(element, display)
{
    if ( document.getElementById(element) )
        document.getElementById(element).style.display = display;
}

function toggle_element(element)
{
    if ( view_element(element) )
        display_element(element, 'none');
    else
    {
        hide_elements();
        display_element(element, 'block');
    }
    return false;
}

function hide_elements()
{
    display_element('header-function-list', 'none');
    display_element('header-online-list', 'none');
}