Hiding the navigation bar like in fullscreen mode

[vannilla]

When entering fullscreen mode (e.g. by pressing F11), the navigation bar, with tabs, address bar, etc. can be hidden by removing focus from it.
I was wondering if there was a way to do something like that without entering fullscreen mode.
Maybe a preference I missed, or an extension.
My system setup is a bit special (Pale Moon is a standard build though!), and being able to hide just the navigation toolbar would further improve it for what I need.
Thank you.

[New Tobin Paradigm]

Write an extension that collapses the browser toolbox.. IF you aren't that concerned about the fancy sliding animation you could just add a splitter with a grippy to the UI via an overlay and then it should be one touch..

Doing the animation or a hover hotspot would be far more complicated..

[vannilla]

So it can be done.
I don't really care about animations as long as I can hide it, so I'll give it a try with the simplest solution.
Thanks!