In the other mozilla extensions its possible to select a filter on the project list. This should be possible in thunderbird aswell. As long as we are working on this plugin a couple of other features can be added aswell.
Technical interpretation
Clean up the source; add an ant build file for easy development
Add the options dialog to the tools menu
Extend the options dialog with a filter tab
Add the filter to the project list
Clean up the layout of the account settings
Simultanious bugfixes/feature requests:
1423321 thunderbird: tab sequence Can't find a way to fix this.