If you look into the source code you may be surprised how simple this little application is. There’s nothing special. There are lines only and text for the numbers. The most interesting thing of this application is its simplicity. The scaling feature is about 5-6 lines of coding. The canvas has a scaling transformation and when its size changes the scale factor is updated.
Avalon is a great developing platform. It would be nice to work with Avalon sooner. I can experience its strength while I developed this tiny application. I recommend learning it for everybody.