This drawing system beautifies your free hand strokes, and predicts your next drawings.
Detailed manual is here.
How to play Drawing lines You can draw a free stroke using left button dragging. The system beautifies it when you finish drawing. Red line is the primary candidate, and magenta lines are secondary candidates. You can select another candidate by clicking a magenta candidate. Primary candidate is settled when you click other area then magenta candidates, or you draw the next free stroke.