var isNS = (navigator.appName == "Netscape") ? 1 : 0;
var EnableRightClick = 0;
if(isNS) 
document.captureEvents(Event.MOUSEDOWN||Event.MOUSEUP);
function mischandler(){
	if(EnableRightClick==1){
		return true;
  	}else {return false;}
}
function mousehandler(e){
  if(EnableRightClick==1){ return true; }
  var myevent = (isNS) ? e : event;
  var eventbutton = (isNS) ? myevent.which : myevent.button;
  if((eventbutton==2)||(eventbutton==3))
  	alert("  \n\nCopyright © Sigma Press. All Rights Reserved.\n\nhttp://www.sigmapress.com\nE-mail: info@sigmapress.com\n\n");
   	return false;
}
function keyhandler(e) {
  var myevent = (isNS) ? e : window.event;
  if (myevent.keyCode==96)
    EnableRightClick = 1;
  return;
}
document.oncontextmenu = mischandler;
document.onkeypress = keyhandler;
document.onmousedown = mousehandler;
document.onmouseup = mousehandler;