Just a word of caution. Tk guarantees to support font families named Courier, Times, and Helvetica (see the '-family' option under "Tk::Font - FONT OPTIONS" for more specific details). From that section of the documentation, you can see that if you specify a font family that is unknown, you may get something that is unwanted, possibly even inappropriate: for example, you could get a serif font when you wanted a monospace font.

In order for your application to look as close as possible to the way you want, I'd recommend specifying a list of font families, in order of preference, and picking the first one that's available on whatever system your GUI is running; put an appropriate supported font family at the end of the list. For this, you'll want the 'fontFamilies()' method (see "Tk::Font - DESCRIPTION").

This is easy to do. I wrote two examples as one-liners; I've expanded them into multiple lines so you see the code more easily.

In the first example, I've used the three families you showed: I don't have Consolas or Lucida Console available; Courier is picked as the best choice.

$ perl -E '
    use List::Util "first";
    use Tk;
    my $mw = MainWindow->new;
    my @font_prefs = ("Consolas", "Lucida Console", "Courier");
    my %font_have = map { fc $_ => 1 } $mw->fontFamilies;
    my $font_best = first { exists $font_have{fc $_} } @font_prefs;
    say $font_best
'
Courier
[download]

In the second example, I've added Luxi Mono to the list: this is a monospace font family that I do have, so it is chosen as the best choice.

$ perl -E '
    use List::Util "first";
    use Tk;
    my $mw = MainWindow->new;
    my @font_prefs = ("Consolas", "Luxi Mono", "Lucida Console", "Cour
+ier");
    my %font_have = map { fc $_ => 1 } $mw->fontFamilies;
    my $font_best = first { exists $font_have{fc $_} } @font_prefs;
    say $font_best
'
Luxi Mono
[download]

I'd suggest putting code along those lines in a subroutine, or maybe even a separate module with font-related utilities. You'd only want to populate %font_have once. Perhaps call it with something like: "get_best_font($mw, $font_prefs_ref)".

See also: List::Util::first(); and fc (that was introduced in v5.16^{[perl5160delta]}; use lc or uc if you're writing for an earlier Perl version).