function doneFn (name, result)
{
   if (result != 0 && result != 999)
     alert("The install didn't seem to work, you could maybe try " +
           "a manual install instead.\nFailure code was " + result + ".");
   else
     alert("Installation complete, please restart your browser.");
}
function install(packageName, fileName)
{
   var xpi = new Object( );
   xpi[packageName] = fileName;
   InstallTrigger.install(xpi, doneFn);
}