Default toggle key is ALT
Bars are automatically shown when press Ctrl+L (open URL) or Ctrl+T (open new tab)
Bars are automatically hidden when press Ctrl+W (close tab)

TODO: 
Options window...


Note:
if you want "shadow install" this extension in your firefox profile:
  1. clone this repo ;-)
  2. create a file in your extensions directory (on Linux usually ~/.mozilla/firefox/profile_name/extensions)  named "gui_minify@alcacoop.it"
  3. add a line in this file with your working-tree path

Enjoy!