Recently I was writing a post about NSButton styles on my blog, and when I got to the part about toolbar buttons (Textured Rounded), I realized that I actually had no idea how to create a toolbar in AppKit, so I had to do some research first. I found some help in this sample project from Apple and this project on GitHub, and then I did some experiments with different combinations of things to see what works where.
This could probably be a whole separate blog post on its own (and maybe I'll make this into one), but for now I've put it here to not make that main article even longer.
Here's what I've found:
There are a few different kinds of buttons you can put in the toolbar: