var message="Sorry: Diese Taste ist hier deaktiviert.";

function clickIE4(){ if 
(event.button==2){ alert(message);
 return false;
  }
  } 

function clickNS4(e){
 if (document.layers||document.getElementById&&!document.all){
 if (e.which==2||e.which==3){
   alert(message);
   return false;
  }
  }
  }

 if (document.layers){
   document.captureEvents(Event.MOUSEDOWN); 
   document.onmousedown=clickNS4;   }
   else if (document.all&&!document.getElementById){
   document.onmousedown=clickIE4;
   }
  document.oncontextmenu=new Function("alert(message);return false")