From now on this add-on will be known as Conversation Manager (you might have noticed the thread title has changed to reflect this).
I have updated the first post with the new zip file.
This version includes inline management of your conversations.
You are now able to select multiple conversations and then perform one of three actions on them.
These actions are 'Leave' a conversation, 'Mark as Read', and 'Mark as Unread'
To install this version, you will first have to un-install the old one and remove all of its files from your server.
Then follow the install instructions which are found on the first post as well as in the ReadMe file in the zip.
Enjoy,
Syndol