All this work done on the Rectangle page has resulted in a page which is teaching material, rather than just documentation.
Exactly the right thing to do with a wiki. And done well. Congratulations.
Thank you, @GordonFindlay, for your kind words. This was a team effort, with contributions from many people both on and off the forum. When I first began working with Lazarus, I found the documentation challenging to understand because I had no prior experience with Pascal. Although I had dabbled in Borland Turbo Pascal, our management decided to switch to Clipper at the time, so that was the end of that.
What I would have appreciated back then was a resource that explained concepts in very simple terms, possibly with a few usage examples to illustrate how to call procedures or functions effectively. And now we have one that hopefully does exactly that.