if (document.layers){
   window.captureEvents(Event.MOUSEDOWN | Event.MOUSEUP)
   window.onmousedown=rightclick;
   window.onmouseup=rightclick;

function rightclick(e) {
   if (e.which == 3) {   // rechte maustaste
      alert('Oh nein! Hier nicht...!');
      return false; 
   } else {
      return true; 
   }
}
}  // ende layers

if (document.all){

function click() {
   if (event.button==2) {
      alert('Oh nein! Hier nicht...!')
   }
   if (event.button==3) {
      alert('Oh nein! Hier nicht...!')}
   }
   document.onmousedown=click
}  // ende all