Hello Arsalan. Thank you for your help. I figured out what the problem was: I used the fakebook theme as a basis for making some color changes because I felt that that would be faster for me than modifying the default theme. In the fakebook theme the sidebar is missing in some wiews, but it looks like that is the desired behaviour. Will change to the default theme now.
Hello Matthias,. It is visible by default can you tell what us your screen resolution http://whatismyscreenresolution.net/
Your width seems smaller then 1300 px https://github.com/opensource-socialnetwork/opensource-socialnetwork/blob/fec7c1d7fd9df55d21e8b765cd29085ed32783d8/themes/goblue/plugins/default/js/goblue.php#L10