I love this great addon, but in Firefox 47 small area at the top of maximized window behaves like invisible window title for left mouse clicks: page links are inaccessible and doubleclick behaves as window restore.
By changing the value of "extensions.bottomui.tabsOnTop" in about:config to true I was able to move the tabs above the toolbar as requested. You might want to add this as an option in you "toolbar settings" in Customize for novice firefox users.
This option is in the Bottom UI's options. As you can see in the screen shot it is called "Tabs Above Navigations Toolbar".
The "Toolbar settings" in Customize is part of my newer add-on called Toolbar Position Changer. It allows you to change the positions of toolbars by dragging and dropping the toolbars in the Customize view. And having this option there would be unnecessary.
I've been searching so long for an addon like this (finally found via google due to name) it's great, works better than i ever imagined. It really helps my back & neck pain! Simple but complete genius. (One interaction: with NoScript menus when hovering over NoScript icon, important when using payment gateways for the first time (rare), so just disable then). I've been using it 2 months now and it feels more genius the longer you use it.
Just click download, and in a moment your tab bar and location bar will move to the bottom of the Firefox window.
I've wanted to try this layout for a long time, because I prefer to focus on the web page content and not on the browser's buttons, tabs, etc. Also, it might help others using this addon if they use keyboard commands to access the location bar (CTRL+L or ALT+D) and to switch tabs (I use the addons SwiftTabs and All Tabs Restorer); using the keyboard, it doesn't matter where those controls are located.
It would be helpful to be able to control which bars are on top: Tab, location, and any other bars at the bottom of the screen, but the default happens to work best for me.
It works. Feels a little strange at first but probably more efficient when I get used to it. I would give 5 stars if it had option to alter the order of the toolbars. Checking/unchecking tabs on top does change tabs toolbar location, still not quite enough.