I've been doing this for a long time, ever since I was able to score a used Wacom Cintiq. I would recommend anything with a screen (Cintiq, Huion, iPad, etc.) over a plain graphics tablet if you can -- it makes things more tactile and immediate.<p>I've (mis)used a number of drawing apps for programming design, including Milton (as in the article), Foundry Mischief, AutoDesk Sketchbook Pro, WonderUnit Storyboarder, Blender, Leonardo, Krita and Xournal++.<p>Mischief, Sketchbook and Storyboarder are either discontinued or no longer under active development. Mischief had a really nice infinite canvas and some nice features for doing presentations across it. You can still get an old Windows version if you look in the... right places. But it's a dead end. Sketchbook has a lot of nice features, but seems like it's all but abandoned. It /is/ available on mobile. They used to have a nice blog where they featured a lot of great artists. Storyboarder is cross-platform and source is available, but packages can't seem to be downloaded any more.<p>The Blender grease pencil tool just gets better and better and works well with tablets. I've used it to do rough sketches and user-interface mockups. Colour selection was a bit clumsy last time I tried, but I think it's been improved since. I think you could say it has an "effectively infinite" canvas. Scriptable, 3D objects are first class.<p>Leonardo is Windows-only, but has pretty nice raster-based infinite canvas. Very responsive and quick. Very easy to do constrained lines and shapes, which can be useful for programming ideation. It's my current go-to, I'm not sure what I'm going to do when I switch to Linux once Win10 is unsupported. Maybe it will run on Wine...<p>Krita is really more of a traditional paint program, but I've still used it for notes and designs even though no infinite canvas. It has a "Comics Manager" bolt on that can be used as a sort of notebook. Scriptable.<p>Xournal++ is a bit of a strange beast. It's intended to be more of a "notebook" application. No infinite canvas, but as many "pages" as you like. It deals with LaTeX, PDF and also pressure-sensitive tablet sketching. It has voice recording and markup features. It's also cross-platform -- I've used on Windows and Linux, and if I can't take Leonardo with me it's probably going to be my new main app. Also -- nice to use when you want to sign a PDF with a "real" signature.<p>Not including things like GraphViz, PlantUML, etc. -- all the apps above are very responsive and support pressure-sensitive sketching, which I think is vital for ideation and exploration.