Rated 4 out of 5 stars
squib January 2, 2012 #
This add-on doesn't touch the thread pane at all, and I tried to add more columns myself and it works fine. Chances are you have something else disrupting the thread pane.
I have checked all my extensions and only when I uninstalled your add-on I can modify the set of columns in the thread pane.
You have developed a very good extension but as you see there is a bug in its code.
I expect that something in your profile is fouled up, since I've tried this on multiple installations and it works fine. In any case, this isn't really the best channel for bug reports, so please file a ticket here: https://bitbucket.org/squib/mail-summaries/issues/new