A modal spellcheck window turns each misspelled word into a popup menu of suggestions. This is pretty typical. Unfortunately, it hides information and forces unnecessary interaction. The user has to click on each word in turn, scan the suggestions, and click again on the right one. The demo shows all suggestions for all misspelled words at once. The user can scan the entire document, suggestions and all, and then correct everything in one fell swoop – click, click, click, click.