Why don't you make a start on a new Tutorial, and let others contribute to the areas you don't already know.

In the last couple of weeks, I've been stunned to find it's possible to not only create a cross-platform GUI program, but to also easily turn it into a Windows .exe

I used Wx for the GUI, and while I haven't needed a progress-bar, I can see that Wx apparently has them - in perl.

To make the Windows .exe, I created a script that calls App::Packer::PAR->new(), just like pp does. And to create the Mac application, I used PrepAPPL (which requires perl and all modules already installed). To make a self-contained application, I believe camelbones should do that, but I haven't looked at it properly.