*grins* Well, I guess with that I can help:
Open data/gui/shortcutwindow.xml in a text editor.
Find the widget for the commands ("<widget name="CommandBox" factory="pawsMultilineEditTextBox">") and then add a "<spellChecker enable="true" r="255" g="0" b="0"/>" line to it. (Can see an example of this in data/gui/bookwriting.xml).
With the "enabled" you can define if you want spellchecker support...so if you want to disable it again you don't have the remove the whole line but only need the change this to "false". The "r", "g," and "b" define the color used for typos..in the example pure red.
This way you can enable the spellchecker for every "pawsEditTextBox" and "pawsMultilineEditTextBox". So if you want spellchecker support in quest notes or guild description...no problem either.
Oh..and as always...sorry windows users, I think after two years the spellchecker still didn't make it to your platform...touch luck.
Edit: Link to my original introduction to the spellchecker:
http://www.hydlaaplaza.com/smf/index.php?topic=40477.0
