Besides portability... and from a Windows via C standpoint.

Speed: There's a bit more setup with a direct Win32 interface than with TK. Also, Windows doesn't manage the windows, letting the program do it; TK helps you in that regard.

Ease of use: Tk you can design dynamically with eaze. Windows? Painful.

Documentation: Two CD's and a few books for Windows, not all of them from Microsoft. Tk? The manpages and "Tcl and the Tk toolkit", but there's also a Perl/Tk book.

It's much better to use Tk than to sink more money into Win32::GUI. You'll be glad you did.

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$Stalag99{"URL"}="http://stalag99.keenspace.com";