Review for Extra Folder Columns by shisho
Rated 2 out of 5 stars
This addon looks cool, and it partly true, but very hard to use because of mixed unit of folder size. It's disgusting to see MB and KB in the same column. 200KB looks much bigger than 90MB. No one needs precise folder size less than 1MB.
This add-on could be better just to add total size of each maixboxes.
To create your own collections, you must have a Mozilla Add-ons account.