my @list_of_files = qw{File Edit Help};
my $regex_to_match_label = qr{LABEL="([^"]+)};
my @menu;

for my $filename (@list_of_files) {
    open my $fh, '<', $filename or die "Can't read $filename: $!";

    my @submenu;
    push @menu, { -label => $filename, -submenu => \@submenu };

    while (<$fh>) {
        if (/$regex_to_match_label/) {
            my $label = $1;
            push @submenu, 
                { -label => $label, -value => sub { generic_dialog($label) } };
        }
    }

    close $fh;
}