The change to require the '-' in front of options, occured when PerlTk upgraded to the latest TCL base. So the old PerlTk was versioned with 800 numbers, while the current version is series 804.

So the code does run flawlessly on the Tk version, on which it was written ..Tk800.xxx. There are many old Tk scripts like that floating around. Just go to the snippets and code sections of perlmonks and look for old Tk snippets from a few years ago. They will all give those errors if you try and run them on Tk804.xxx. It's simple to fix the scripts.

The same is true of Gtk2 scripts..the libraries are always being improved, and sometimes it breaks "old syntax".