World editor

key map on level editor

... [p]lace currently selected ding on current cursor position, on the first available and suitable layer

.... [o]bliterate topmost ding on current cursor position. exposes universe if floor is deleted

.... [f]loodfill enclosed area with currently selected ding on lowestmost available layer (does not vertically flow around obstacles even if placed ding would allow)

.... rotate in place (orientable only). Mousewheel supported

.... show Ding sheet

<->.... select previous ding from toolbox

<+>.... select next ding from toolbox

. select next category/group of dings from toolbox

. select previous category/group of dings from toolbox

. toggles navigation

<↓→↑←↑> navigate

.... loads from a file

.... saves to a file. prompts for location and name the first time

.... save as

Trivia: to have symmetric building blocks, we opted for a standard constituent block size of 49 x 49
In your face, 70's processor architecture!
Eat that, byte alignment based compiler optimizations!