In that case Tk is a pretty clear choice. It is light weight for a job such as you describe and the somewhat non-native look doesn't matter at all. Actually you'd probably find you have it knocked out in crude form in an hour if you let pack manage the layout for you.

The Tk documentation is ok, but tends to be a bit scattered with some bits in non-obvious places. Important bits to be familiar with are Tk::options, Tk::pack, Tk::Radiobutton, Tk::Text and Tk::Label.

If you would like a light weight starting point take a look at Utility to capture parameters and perform a task or Tk Tutorial, Featuring Your Very Own "Perl Sig/OBFU Decoder Ring" for a tutorial that explores a little more of the functionality.