I use mostly command line tools, but sometimes browsing a directory tree is more easy using GUI. In PCManFM I could use the arrow keys to walk the tree and left arrow and right arrow would open a closed tree node (as did explorer on Windows XP).
Nautilus requires to use Return to open a directory if selected (using up and down) and I have not found a way to close using a key.
Is there a way to configure nautilus so I can do all navigation, in the left pane tree, with the arrow keys instead of using the mouse?