Just discovered a great feature in the upcoming version of Firefox. I downloaded and installed Firefox 2.0rc3. As I was editing some Typoscript in the back end of TYPO3, I noticed many of the words had a red dotted line underneath them. All of the words that were underlined were coding-type words like "stdWrap." At that point I realized that Firefox can now check spelling in forms.
Even better, if you control-click (Mac) on the misspelled word, a context menu will come up and give suggestions that you can select. I use the mac version of Firefox, but I am sure the Windows version does the same thing but probably with different key combinations.
Now, when you are in a RTE field in TYPO3, you will see misspelled words underlined but the context menu will not come up because it is superseded by a RTE context menu. But there is a way around this.
I never use the RTE context menu so I disabled it using this code:
RTE.default.disableContextMenu = 1
This allows the Firefox context menu to appear instead of the RTE context menu.
To me, this is a great feature. Funny the things you discover just by keeping your eyes open.