I think the bar should disappear altogether if you don’t have anything in the Bookmarks folder. Put the Other Bookmarks folder to the left or right of the search bar. Closing the dang bookmark bar gives me about 3 more lines I can view without scrolling and just looks cleaner! That’s why I’m loving ctrl-shift-b, didn’t realize how much that bookmark display bugged me until I could remove it… would be nice not to have to do even that by just redesigning the layout…
Edit: Sort of like this Feature Request 
Although I would have some minor changes. Just a note, the side panel would work for me if you had the option to move the bookmarks and folders. Right now, it is just a static display and that just doesn’t work.