function lib_bwcheck(){
 this.ver=navigator.appVersion
 this.agent=navigator.userAgent
 this.dom=document.getElementById?1:0
 this.opera5=(navigator.userAgent.indexOf("Opera")>-1 && document.getElementById)?1:0
 this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom && !this.opera5)?1:0; 
 this.ie6=(this.ver.indexOf("MSIE 6")>-1 && this.dom && !this.opera5)?1:0;
 this.ie4=(document.all && !this.dom && !this.opera5)?1:0;
 this.ie=this.ie4||this.ie5||this.ie6
 this.mac=this.agent.indexOf("Mac")>-1
 this.ns6=(this.dom && parseInt(this.ver) >= 5) ?1:0; 
 this.ns4=(document.layers && !this.dom)?1:0;
 this.ns=this.ns4||this.ns6
 this.bw=(this.ie6 || this.ie5 || this.ie4 || this.ns4 || this.ns6 || this.opera5)
 return this
}
var bw=lib_bwcheck()