Very useful extension. Especially since Firefox's default boookmark manager is not very good. I have a few suggestions.

The big:
1. Optionally allow the Explore tab to remember previous state after refresh so that it opens in the last folder you were in + the side folder tree retains it's collapse/expanded states
2. Ability to collapse/expand folders in the dashboard by clicking the title header
3. Option to show subfolders of folders in dashboard.


The small:
4. Tab should have a proper tab title and favicon
5. Middle click should serve to open bookmarks in background, that way ctrl+click could be used to select multiple bookmarks for batch editing. This is the standark mouse button functonality for bookmark managers.
6. Option for side folder tree: Don't expand folders on click. (However auto expand will still work to show current folder path if you click on a subfolder in the mainview.)

I would personally like #1 and #5 most. Regardless this is a really great extension, especially on Firefox.