NumberSpinner=function(id,increment,min,max){
    this.id=id;
    this.element=document.getElementById(id);
    this.MinValue=min;
    this.MaxValue=max;
    this.Increment=increment;
};
NumberSpinner.prototype.Up=function(){
    var x=parseInt(this.element.value)+this.Increment;
    if(x>this.MaxValue){x=this.MaxValue;};
    this.element.value=x;
};
NumberSpinner.prototype.Down=function(){
    var x=this.element.value-this.Increment;
    if(x<this.MinValue){x=this.MinValue;};
    this.element.value=x;
};