function clickIE(){
    if (document.all){
        return false;
    }
}

function clickNS(e){
    if(document.layers||(document.getElementById&&!document.all)){
        if (e.which==2||e.which==3){
           return false;
       }
   }
}

if (document.layers){
    document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;
}
else{
    document.onmouseup=clickNS;document.oncontextmenu  =clickIE;
}