This is the first time I've seen TODO as a ligature, and I am really into the idea. Is this something you can add to existing fonts? Does anyone have any recommendation for a good programming font that does this?
I could do without operators being condensed into ligatures, but that's just me. The gigantic triple equals strikes fear into my C programmer heart
However, many editors can accomplish the same goal by highlighting or changing the text colour of todos.
You could make it have the outline thing if you tweak your theme. I wouldn't start installing or hacking your fonts to get this kind of stuff.
[1] https://news.ycombinator.com/item?id=32746064 (and I only realized that I made this comment on the thread about your older font, oh...)