I don't feel that strict can be stressed too much, but I do often see production code have the -w removed. Running with warnings enabled is good and helpful for development and testing, but the warnings are rarely helpful to the end-user, unless your user-base is also Perl-savvy.

As for the "used only once" cases, that's hard to address without some code in front of me. I've written several applications with Tk, and in all the cases I can remember I had to use an object value more than once, even if all I did was use it to call pack after creation. If you are crafting your constructor calls such that it threads through from new --> pack in one (long, complex) statement, then maybe you don't need to be assigning the value to a variable? Why not just:

<code> my $MW = Tk::MainWindow->new();

$MW->button(-text => 'Quit', -command => sub { exit })->pack; <code>

--rjray