Rated 5 out of 5 stars

great addon.keep up the good work. a button to remove these LSO and other objects would be useful.

This review is for a previous version of the add-on (1.14a). 

The requested button already exists.

Go to the FireFox tools menu and click the BetterPrivacy item to open the options dialog. You will see two buttons to remove LSO cookies. (remove single cookie or all).
DOM storage objects cannot be deleted while FireFox is running nor at startup nor at shutdown (because of a bad technical limitation). So the only way to prevent DOM storage is to disable it completely. However, you still can use an external filemanager to delete the webappsstore.sqlite file, but only after you have finished your FireFox session).