Using dconf-editor I tried enabling
org -> gnome -> nautilus -> list-view -> use-tree-view
but even after the check box is selected, plus a reboot, it still doesn't switch to the tree view on the side bar.
In previous versions of Nautilus / Ubuntu the side-pane-view setting used to be in the window-state section (which is now missing)
I'm I missing something, or is there no way to enable Tree View on the side bar in 14.04?
Is there a way to manually create the missing entry back in window-state ?