When misspelled word is corrected with the spell checker, and the word is just before the comment range end, the comment range end is moved after the previous word.

Steps to reproduce:
1. Open RichTextBox and type the following sentence: "This sentence has a wrong speling".
2. Select the entire sentence and click "New Comment" button.
3. The comments range start marker displays before "This...." and comment range end marker displays after "...speling"
4. Right click on word "speling" to change "speling" to "spelling"
Result: The spelling gets fixed as expected, but the comment range end moves before the word "spelling".