almost perfect for me Rated 5 out of 5 stars
I found this after using a Stylish style to do similar similar to the addon bar (making it take up only the space that has icons), but this is far better, with the minimization. :)
For my use, the only issue I had, which is not really the fault of this extension, was that 2 of my extensions use the older status bar placement, so were unavailable by default. Furthermore, one (ScrabBook Plus, as well as the original ScrapBook) has different commands for its status bar than toolbar icon. I spent hours trying to sort this out because I rely on its editor often (only accessible AFAIK by the status bar icon). I finally managed to be able to use it without this extension through an old extension named keyconfig, whose author had the actual code to hot-key a shortcut to the editor posted in one of about 140 pages of a discussion. Again, this is not the fault of this extension, but of an outdated method used by other extensions, so I won't drop a star in my rating.. However, it's still a concern for people who rely on functions of extensions that pose this conflict, as the item set to be a status bar icon isn't doesn't always serve the same function as a toolbar icon that can be added to the addon bar manually.
So, great work, but any possible future plans to make it play nicer with other extensions would be of great benefit to those who use otherwise conflicting extensions.