Proofing
Twain offers three writing aids while you edit the source: spelling, grammar, and a light style check. They are independent toggles in the Format menu.
Editing is part of Twain Pro, so the proofing toggles are usable only with Pro. Without it they stay greyed out, and whatever values are currently stored apply and cannot be changed.
| Toggle | Default | What it does |
|---|---|---|
| Check Spelling While Typing | On | Underlines misspelled words, using the built-in macOS spell checker |
| Check Grammar With Spelling | Off | Adds macOS grammar checking |
| Highlight Style Issues | Off | Marks a couple of common writing snags (see below) |
The proofing toggles live under Format and can be changed while you are editing a document's source. Spelling and grammar use the same system dictionaries as the rest of macOS. All three aids apply to the raw source pane only: editing a Markdown document in the rendered pane has spell checking switched off and draws no style underlines, so use Raw Source (⌘2) or Side-by-Side (⌘3) when you want to proof as you write. None of these aids ever changes your text on their own; they only mark suggestions.
Style issues
Highlight Style Issues adds a thick orange dotted underline (it never edits your text) to two things:
- Filler words, from a fixed list of fourteen: very, really, quite, rather, fairly, somewhat, pretty, basically, actually, simply, just, essentially, virtually, arguably. Matching ignores case and only matches whole words.
- Repeated words, where the same word (ignoring case) appears twice in succession. Punctuation or a line break between the two does not stop the second one being marked.
The underline is the whole of the feedback: Twain does not show a tooltip, popover, or explanation for a marked word, and offers no correction for it.
These marks are purely visual. They do not affect saving, export, or the rendered output.