Press the SPACEBAR to hide pointer and stop drawing. Press the V KEY to resume drawing. Press the B KEY to show the pointer. Press the P KEY to clear the screen. Press the A KEY to lower the shade, and D KEY to raise it. Press the LEFT ARROW to lower the size, and the RIGHT ARROW to raise it. Move your CURSOR around make rainbows. Press the FLAG to clear the screen.
You can make cool rainbow tubes by slowly dragging your cursor. Mess around with the size, and come up with ideas! The colours are constantly changing.