if(typeof(Prototype) != "undefined" && Prototype != null)
{
    if(typeof(Position) != "undefined"
        && Position != null 
        && typeof(Position.positionedOffset) != "undefined")
    {
        Prototype.Position = Position;
    }
    else
    {
        alert("prototypeSafe.js must be included immediately after prototype.js");
    }
}