function MouseDown(e)
{
   mt = 1;
   if ((document.layers) || (navigator.appName == "Netscape")) {
      mt = e.which;
   } else {
      mt = event.button;
   }
   if (mt != 1) return false;
}

function NoContextMenu() {
   if (document.layers) document.captureEvents(Event.MOUSEDOWN);
   document.onmousedown = MouseDown;
   document.oncontextmenu = MouseDown;
}