Looking at the heat map, what does surprise me is how he never uses Escape or ^[. How does he managed to move out of Insert mode? My [ key is starting to wear out due to such heavy use..
I don't use vim, but from the parsing example he gives in the post, I'm guessing he uses C-c:
`Mihere's some text^Cyyp$bimore ^C0~A.^C:w^M:q
[…]
> The lexer correctly determined that I started in normal mode by navigating to a specific buffer using the `M mark, then typed here's some text in insert mode, then[…]
He may have it set up the way I do: if I tap Ctrl rather than holding it, it sends Escape. If that's the case, his heatmap might be lumping Escape and Ctrl together.
