## fetch a single file using getOpenFile
sub get_single_file {
  ## read from the command line?  from the web?
  ## unless (($_[0] and -e $_[0]) or ($_[0] and $_[0] =~ /^http:/)) {
  require Cwd;
  #local $Tk::FBox::a;
  #local $Tk::FBox::b;
  my $path = $current_data_dir || Cwd::cwd;
  my $types = [['All Files',            '*'],
	       ['data files',          ['.dat', '.xmu']],
	       ['chi(k) files',         '.chi'],
	       ['Athena project files', '.prj'],
	      ];
  if ($Tk::VERSION > 804) {
    my $file = $top -> getOpenFile(-filetypes=>$types,
				   #(not $is_windows) ?
				   #  (-sortcmd=>sub{$Tk::FBox::a cmp $Tk::FBox::b}) : () ,
				   -initialdir=>$path,
				   -multiple => 1,
				   -title => "Athena: Open one or more data files");
    $file ||= [];
    return @$file;
  } else {
    my $file = $top -> getOpenFile(-filetypes=>$types,
				   #(not $is_windows) ?
				   #  (-sortcmd=>sub{$Tk::FBox::a cmp $Tk::FBox::b}) : () ,
				   -initialdir=>$path,
				   -title => "Athena: Open a SINGLE data file");
    $file ||= q{};
    return $file;
  };
};