Very Cool Add-on! Rated 5 out of 5 stars
First of all, thanks for the time and work that you put into your Shortcut Toolbar.
I believe that there was a similar one a long time ago but I guess that it was abandoned.
I use a hack that is very similar to what your extension does. I paste the address (from the Address Bar in Windows) of a local folder that I want to display in Firefox into the location bar and then after Firefox opens that folder/directory I then view that page in IE Tab and bookmark that page and so now I can open files and folders inside of Firefox whenever I want to.
That's a lot of work to do but the main advantage is that I can open and run different files right inside of Firefox. The best example is that I can have Firefox open a .txt file right inside of Firefox by dragging the file to the tab bar. I can also edit that file within Firefox by using the Text Formating Toolbar Composer. Another example is I can open and manipulate and edit photos and graphics by opening the graphic inside of Firefox, then I can use add-ons to edit the graphic.
So with all of that being said, I have a request to have folders open up in Firefox and not just launching the folder in Window.
Also, I'd really like to have the ability to remove the text from beside the icons in your extension and replace the text with tooltips.
In any event, this is a highly desirable add-on.
Thanks and good luck.