Press 0 to toggle edit mode. Press 1, 2 or 3 to toggle the layer/onion mode. Hold space to move the edit tile on the right as you move your cursor or player. Use the arrow keys keys or WASD keys to move. Your map stays the same (so you can continue playing). Have fun!
Updates: You can now move X2 as fast in the editor Collisions! Note that I will replace this project as I have restarted making it, so your maps will be gone. But you can copy your grid list so that you can play it again!