Rocks'n'Diamonds includes a mighty level creator with which you can realize  many game  ideas and other things. 3 years ago I  produced "game inside" (a simulation of R&D inside a level) and later I asked myself: Is it even possible to build  a level in which you can edit and play a level ?

The answer is: Yes, it is. Edit inside" is a gadget to simulate  Edit-,  Load-  and Save processes inside an R&D Level. Nobody would ever use such an "inside Editor" for normal level design  -  it's simply another example for the possibilities of the "custom elements".