Rated 5 out of 5 stars

@Ed

you have to go to yourprofile\extensions\extra-cols@jminta_gmail.com\chrome\content there you find the main.js. Open it with an texteditor an search:
switch (aColName) {
case “folderNameCol”:
Then delete the three lines wich starts with - in front of them. After that insert the lines with the + ...

Don´t forget to save the file an then start Thunderbird.

This review is for a previous version of the add-on (0.3).