Pressing different keys draws different things. P: Draws quadratic equation ax^2 + bx + c. O: Draws quadratic equation ax^2 + bx + c inversed along x = y. I: Draws a big blob of ink where you tap, changes size where you drag (Size Divider divides the distance from the pencil tip). U: Draws a polygon. Y: Changes the color of the pen. (No on change color disables rainbow) T: Highlights an x-y coordinate (hold T to make the point bigger).
