function BwCh(){
   this.ver=navigator.appVersion; 
   this.agent=navigator.userAgent;
   
   this.dom=document.getElementById ?1:0;
   this.all=document.all ?1:0;
   this.lay=document.layers ?1:0;
   
 //  this.ie=(this.ver.indexOf("MSIE")>-1)?1:0; 
 //  if (this.ie) {
 //    this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom)?1:0;
 //    this.ie6=(this.ver.indexOf("MSIE 6")>-1 && this.dom)?1:0;
 //    this.ie4=(this.all && !this.dom)?1:0;
//   }
   this.opera=(this.agent.indexOf("Opera")>-1) ?1:0;
   if (this.opera) {
     this.o5=(this.opera && this.agent.indexOf("Opera/5")>-1) ?1:0;
     this.o6=(this.opera && this.agent.indexOf("Opera/6")>-1) ?1:0;
     this.o7=(this.opera && this.agent.indexOf("Opera/7")>-1) ?1:0;
     this.o75=(this.opera && this.agent.indexOf("Opera/7.5")>-1) ?1:0;
     this.o8=(this.opera && this.agent.indexOf("Opera/8")>-1) ?1:0; 
   }
   this.ns6=(this.dom && parseInt(this.ver) >= 5) ?1:0;
   this.ns4=(this.lay && !this.dom)?1:0;
   this.konq=(navigator.appName == "Konqueror")?1:0;
   this.mac=(this.agent.indexOf("Mac")>-1) ?1:0;
   this.bw=(this.ie || this.ns4 || this.ns6 || this.konq ||
            this.opera|| this.all || this.dom || this.lay);
   return this;
}

var b = new BwCh;

//alert(b.ns4+"; "+b.dom+"; "+b.ie);

var dim = ( b.dom && !b.opera) ? "px" : "";