Hide BookmarksBar is broken on Nightly

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Install Firefox Nightly
2. Install the extension
3. Set-up it to auto-hide the bookmarks tab and show it again on new tabs

What is the expected output? What do you see instead?
The extension to keep working after the recent Nightly changes to the bookmarks 
system.

What version of the product are you using? On what operating system?
Hide BookmarksBar 3.3. Firefox Nightly 23.0a1.

Please provide any additional information below.
I know it's not okay to report issues with Nightly, but it seems that they 
changed the internals of the bookmarks system. They've replaced the bookmark 
star with a toolbar button, for example.

Original issue reported on code.google.com by [email protected] on 25 Apr 2013 at 2:42