Review for Get Selected Messages by Rod Dav4is
Rated 3 out of 5 stars
Has the right idea, but the button needs to be reformatted to occupy less real estate on the toolbar. Put the title /below/ the button icon instead of /beside/ it. Also the title could be shorter: "Get all new" instead of "Get all new messages".
To create your own collections, you must have a Mozilla Add-ons account.