Secrets in the levels

Sometimes, when I'm in level editor, i find several secrets. I shall now post the ones I found so far, along with which level I found it.

Tell me if there are others.

[mod]Added spoiler tags. While secrets in all KS levels can be viewed in the Editor, describing them still counts as a spoiler. Please use spoiler tags next time[/mod]

What are the coordinates of these two?

I like adding easter eggs and other stuff such as well hidden staff rooms in my levels.
I already knew the one in A strange dream.

Oh, it could be in A Strange Dream as well. It is the level that you can go round (if you go left, eventually you'll get to the start of the level again)

there is a secret ending in the machine but you'll need all 4 keys to open the path to it.

Just checked which level it was again, and indeed its A strange Dream.