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; 
  } 

  document.oncontextmenu=new Function("return false")