498: GLScanline, Experiment!
499: Agg Scanline methods meets OpenGL!
501: DrawPoint
502: StrokeWidth
504: CanvasSmoothMode
505: draw with VBO 1

experiment
506: VBO2
508: VBO, 2 sep buffers

ArrayList<VertexC4XYZ3I> mySinglePixelBuffer,  myLineBuffer
511: VertexC4V2S, VertexC4V3I
513: Tess,  FillTriangles
514: prepare another tess listener
515: VBO bind/unbind buffer
516: split CanvasGL2d code file
517: prefers GL.DrawArrays
518:   FillWithColor(), DrawWithColor()
520: Arc
521: Arc.SetStartEndLimit()

precise start and stop arc point
522: add BezierCurve
256: sag style arc, Not complete
527: svg style arc