Review for Extra Folder Columns by Ian
Rated 3 out of 5 stars
This does work with 3.1.2 but:
When you apply columns reccursively downwards there looks to be a limit of 3 layers after which the columns are displayed with their default settings.
Also, if you delete the "*.msf" files the column information is removed.
gyc - Try clicking the icon in the right had display pane which has the column heading tooltip "Click to select columns to display"
To create your own collections, you must have a Mozilla Add-ons account.