function menu_active( id )
{
    menu_set_all_inactive();
    
    var obj;
    
    obj = document.getElementById( 'menu_top_left_' + id );
    obj.className = 'submenu_left';
    obj = document.getElementById( 'menu_top_right_' + id );
    obj.className = 'submenu_right';
    obj = document.getElementById( 'menu_top_bg_' + id );
    obj.className = 'submenu_bg';
}

function menu_set_all_inactive()
{
    var objs = document.getElementsByTagName( 'td' );
    
    for( var i = 0; i < objs.length; i++ )
    { 
        if( objs[i].id ) {
            if( objs[i].id.substring(0, 14) == 'menu_top_left_' )  { objs[i].className = 'submenu_inactive_left'; }
            if( objs[i].id.substring(0, 15) == 'menu_top_right_' ) { objs[i].className = 'submenu_inactive_right'; }
            if( objs[i].id.substring(0, 12) == 'menu_top_bg_' )    { objs[i].className = 'submenu_inactive_bg'; }
        }
    }
    return true;
}