The brush always follows your mouse cursor. Press W to paint and press S to stop. Press the space bar to clear your work and press E to erase some of your work. Size: 0 is smallest, 200 is biggest. Press D to increase size and the A to decrease the size. Color: 0 = Red, 25 = Orange, 50 = Light Green, 100 = Light Blue, 125 = Dark Blue, 150 = Purple, 175 = Pink, 200 = Red. Press V to increase the color number and press C to decrease the number. Press B to toggle black and color. Shade: 0 is darkest, 100 is lightest. Press X to increase the shade and Z to decrease the shade. Post in comments what you like, don't like, or have suggestions for. Thanks!
This is one of the projects that I made at the e-Comm day camp. I improved it and it is now much better. All the work and all ideas on navigation, color, and shade are totally my own. Credit to @Scratchwei for eraser workings.