# have now read through all files once and stored every
# Nth position in @tells
my $dirpos = @tells / 2; # start in the middle
my $browsing = 1;
while ($browsing)
{
   my $action = "";
   $f = $dir->seek($tells[$dirpos]); 
   # code to go here to read next N files and display
   # results to user.
   # Come back here when we have an submit from the user
   # and $action set to the result.
   if ($action eq "pageforwards")
   {
      #should check for end
      $dirpos++;
   }
   elsif ($action eq "pagebackwards")
   {
      #should check for start
      $dirpos--;
   }
   else
   {
      # do other actions
      $browsing = 0;
   }
}