This might be a stupid question but it troubled me for 1 hour and I'm still unable to solve. I accidentally clicked something in nautilus file management after which the sidebar occupies half of the page. [See attached screenshot] I tried to drag the right boundary of sidebar to make it narrower but it can't be dragged anymore left. How could I reset it to normal? Thanks in advance. sidebar_occupies_half_of_page
Update: The problem remains even after I upgraded Ubuntu from 16.04 to 18.04. stuck_in_middle I'm able to drag the separation bar to the right, however, whenever I try to drag it to the left, it get stuck in the middle (see gif).