function Is() {
    agent  = navigator.userAgent.toLowerCase();
    this.major = parseInt(navigator.appVersion);
    this.minor = parseFloat(navigator.appVersion);
    this.ns    = ((agent.indexOf('mozilla')   !=   -1) &&
                 ((agent.indexOf('spoofer')   ==   -1) &&
                 (agent.indexOf('compatible') ==   -1)));
    this.ns2   = (this.ns && (this.major      ==    3));
    this.ns3   = (this.ns && (this.major      ==    3));
    this.ns4b  = (this.ns && (this.major      ==    4) &&
                 (this.minor                  <= 4.03));
    this.ns4   = (this.ns && (this.major      >=    4));
    this.ns6    = (this.ns && (this.major     >=    5));
    this.ie    = (agent.indexOf("msie")       !=   -1);
    this.ie3   = (this.ie && (this.major      <     4));
    this.ie4   = (this.ie && (this.major      ==    4) &&
                 (agent.indexOf("msie 5.0")   ==   -1));
    this.ie5   = (this.ie && (this.major      ==    4) &&
                 (agent.indexOf("msie 5.0")   !=   -1));
    this.ie55  = (this.ie && (this.major      ==    4) &&
                 (agent.indexOf("msie 5.5")   !=   -1));
    this.ie6  = (this.ie && (this.major      ==    4) &&
                 (agent.indexOf("msie 6.0")   !=   -1));
	}
	
	var is = new Is();
	var doc,sty,htm,xpos,ypos;
	
	if(is.ns4) {
		doc = "document";
		sty = "";
		htm = ".document"
		xpos = "e.pageX";
		ypos = "e.pageY";
	} else if(is.ie4 || is.ie5) {
		doc = "document.all";
		sty = ".style";
		htm = ""
		xpos = "event.x";
		ypos = "event.y";
	}