Hi,
Just wanted to bring this to your attention.
Not a train smash just something odd i found where it would occasionally show you the engine content.
Its minor and only happens once in a while for no apparent reason.
This happens when you click to view a reference to an object that is in the engine folder. Viewing of the engine folder can be toggled on and off in the content browser.
It also can happen if you click on a folder in the structure and then collapse the parent.
Seems to be a known issue. I had made a post about it over 8 month ago… 
Hi.
This happens when i change folders or try to open one of my assets. I am not viewing the engine folder content.
If i was viewing engine folder information it would show the engine folder under the list you see on the left.
But as you can see it is not displaying it. Which is why i think its a bug.
EDIT:
Oh i see you are correct KVolger. It does indeed reproduce every time when you do that