Many common words with apostrophes fail spell checking (isn't, shouldn't) while others pass (don't, can't). Word traversal (GetCurrentWord, etc.) breaks words apart on apostrophes.
Hello Mark, Please follow the following item for RadSpellChecker which refers to the same problem: http://feedback.telerik.com/Project/143/Feedback/Details/131798-contracted-negative-forms-are-not-recognized-by-the-spell-checker. I'm declining this item to avoid duplication.