I really like the way Scrivener displays inline annotations and footnotes, through a bubble font style. It’s nice working with them.
In Word, I have a template style I created for the same commenting purpose. It uses red text, on top of a pale yellow or light gray background, as a direct attribute of the font, via the Style. It’s bound to a key that toggles it on and off, when either typing or selecting. It’s a character style.
Scrivener’s annotations perform the same trick, using red text along with an under-and-overlining “bubble” style, applied to text as it’s typed. I’ve bound it here to the same key as in Word (Ctrl+Shift+C, for Comment, and because it falls so easily to hand), which makes it easy to get in and out of. I was happy discovering you can put an annotation button on the format toolbar.
On Word, because the style has a name, I can easily use it in a search (which I don’t do a lot of, as it turns out), and more generally work with it as a different category of verbiage than plain old normal (Normal happening to be the default name of the default style in Word’s default template.) And likewise here at LitNLat, where a “built-in” annotation style can easily be a search variable.