Affects Version/s: Minecraft 1.8.7, Minecraft 15w43b
Fix Version/s: Minecraft 15w49a
The root menu (the one activated by holding shift and hitting f3) does not disappear if you log out of a server.
To recreate, simply activate it in a server and log out (I don't know if it works for LAN if someone joins and then logs out).
Here is a link to a video tutorial: