[devote]

function findPosY(obj) {
    if ( !obj ) return 0;
    var curtop = 0;
    if ( obj.offsetParent ) {
        while (1) {
            curtop += obj.offsetTop;
            if ( !( obj = obj.offsetParent ) ) {
                break;
            }
        }
    } else if ( obj.y ) {
        curtop += obj.y;
    }
    return curtop;
}