The Google Toolbar spellchecker interacts weirdly with the Rich Text editor. If the spellchecker flags the word "misspelldd" and you click it and select the correct spelling and then click the Wiki Markup tab, you end up with the popup text in the wiki markup like so:

misspelled
another line

misspelled
misspell dd
misspell-dd
misspells
misspell
Edit...
Revert to "misspelldd"

I've also seen it interact weirdly with a bullet-list created in the Rich Text editor. If a misspelled word is in the list (the first word on the line, I think), it will cause that word to get pulled up into the end of the previous line, i.e., the following:

• One two three
• Four fiive six

became:

• One two threeFour
• fiive six

Note that this only occurs if you type the above bullet-list into the Rich Text editor. If you copy-and-paste the above text into the Wiki Markup editor, and then switch to the Rich Text tab before clicking the Google Toolbar "Check" button, then it works fine (go figure).

Note that this only occurs when you use the Google Toolbar spellchecking in the Rich Text editor. If you use the spellcheck in the Wiki Markup editor tab, then it works fine. Hence, doing your spellchecking in the Wiki Markup tab is the work-around for this issue.

Note that after I reproduced this problem, it seemed like the Google Toolbar spellchecking no longer worked (no longer found misspelled words), and I had to re-start Firefox to re-create again. So, you may want to restart Firefox before trying to reproduce this issue.