I can easily reproduce this behavior in a fresh install of Ubuntu GNOME Xenial:
(1) Open Nautilus
(2) Open Location options using the hamburger icon
(3) Left click on any open space - either on the desktop or on the blank background of the Nautilus window
(4) You'll now find that the Nautilus UI is totally unresponsive
(5) If you then right-click on the Nautilus tab in the top bar responsiveness returns to the UI
Additionally if you have System Monitor running on the same desktop you'll see the CPU usage nearly pegs out (see screenshot).
I can easily reproduce this behavior in a fresh install of Ubuntu GNOME Xenial:
(1) Open Nautilus
(2) Open Location options using the hamburger icon
(3) Left click on any open space - either on the desktop or on the blank background of the Nautilus window
(4) You'll now find that the Nautilus UI is totally unresponsive
(5) If you then right-click on the Nautilus tab in the top bar responsiveness returns to the UI
Additionally if you have System Monitor running on the same desktop you'll see the CPU usage nearly pegs out (see screenshot).