I just switched to Sublime Text as my new editor. If I open the sidebar it shows the opening file, but what I want is a file navigation sidebar, is it possible to change that without downloading plugins?
You have to add a folder to the Sublime Text window in order to navigate via the sidebar. Go to File -> Open Folder... and select the highest directory you want to be able to navigate.
Also, 'View -> Sidebar -> Show Sidebar' if it still doesn't show. In the new version, there is only an 'open' menu and no separate option for opening a folder.