These are the keyboard shortcuts for the editor:

GENERAL:

ESC - bring up the menu


EDITING MODE:

ARROW KEYS - move the cursor
CTRL - place an object
SHIFT - delete an object
A and D - select previous/next object
W and S - change the cursor step size
B - send object under cursor to the back of the current layer
+ and - - select active layer
SPACE - activate selection mode
V - paste objects from clipboard
T - switch to game mode for testing
H - switch to game mode with Nikki starting at current cursor position

As the objective in every level is to switch on all the switches, you should place at least one switch in your level. Also don't forget to put Nikki in it.


SELECTION MODE:

ARROW KEYS - move the upper right corner of the selection box
C - copy highlighted objects
X - cut highlighted objects
SHIFT - delete objects in selection (without changing clipboard contents)
W and S - change the cursor step size


OBJECT EDIT MODE:

Some objects allow you to edit special attributes. To do that, select the object by hovering the cursor over it (the according object under the cursor will be indicated in the lower right corner of the screen), go to the menu with ESC and select "edit object".

Depending on the object you can configure different attributes. At the moment you can edit:

 - Terminals
    Configure which robots will be accessible via the terminal

 - Moving Platforms
    Configure the path of the platform