document.oncontextmenu = new Function(" return false; ");
if(document.layers)
{
  document.captureEvents(Event.MOUSEDOWN);  
  document.onmousedown= new Function("if (document.layers||document.getElementById&&!document.all){if (e.which==2||e.which==3) return false;}");
}
else
if (document.all&&!document.getElementById){
  document.onmousedown= new Function("if(event.button == 2) return;");
}