works well Rated 4 out of 5 stars

update. ok, got it working. Thanks to developer for instructions. seems to work, except cannot toggle hide/show for menu bar. worth keeping though.prior comment removed.

update: looking at this again hoping it's been fixed, but still does not toggle , for example the menubar. so basically I click the button to hide the menubar which is all the addon seems to do, it won't reshow the bar again. using FF25.

You have to add it in the toolbar you want. To do that go to view > toolbars > customize and drag one of the buttons ( Quitoolbars, or Quitoolbars menu ) to the desired toolbar. You can also right click on an empty space in a toolbars and select customize.