Extra Folder Columns is a Thunderbird extension for users who want the multiple-columns view that Thunderbird 2 allowed.
How to Install in Thunderbird:
1. Right-click the link below and choose "Save Link As..." to download and save the file to your hard disk.
2. In Mozilla Thunderbird, open Add-ons from the Tools menu.
3. Click the Install button, and locate/select the file you downloaded and click "OK".
- Fixes an issue with latest Thunderbird builds (22 and later) where Folder Pane icons weren't displayed correctly.