Developer reply by Ian Fraser
Rated 1 out of 5 stars
The button appears but it removes all the other buttons (reply, forward etc...) and there is not way to put them back. It becomes the ONLY button available. I had to remove it ...
You should be able to right click next to the 'Toggle Headers' and get a 'Customise...' menu. Select this and you can add back the missing buttons. I don't know why they disappear :-(
To create your own collections, you must have a Mozilla Add-ons account.