use Tk;
use File::Spec;

$top = MainWindow->new();

my $menubar = $top->Menu(-type => 'menubar');
$top->configure(-menu => $menubar);

my $filemenu = $menubar->cascade(-label => '~File', -tearoff => 0);
$filemenu->command(-label => '~Report extract',        
                   -command => [\&report_extract],
                   );

$filemenu->command(-label => 'E~xit',        
                   -command => [sub {exit}],
                   );
print STDERR "there's a tiny window open, it's small but it's there\n";
MainLoop();   

sub report_extract {
   my $tmpdir = File::Spec->tmpdir();

   open (F, ">$tmpdir\\xx.csv") || die $!;
   print F "aaa,bbb,ccc\nddd,eee,fff\n";
   close F;
   my $cmd = "start $tmpdir\\xx.csv";
   print STDERR "running $cmd\n";
   `$cmd`;
}