For hit boxes press p and you will find some circles that are dark put your mouse on a circle and press 1 on it and then it will make a pin! And press x on a circle if you make a mistake. Press 0 to make the level editor show press it again and it will hide. To remove the tile you put on the screen just press the e key on the grass. To turn on the onion mode go on the level editor and find the layer variable on the top left and it will say one, two, or three. Press that number like one, two, or three. And then it will turn on onion mode. To make your stuff faster just hold space and click and move your mouse around and clicking at the same time. Move with the arrow keys or the WASD.
Thanks to @griffpatch for the youtube tutorial.
