- GetPlotWidth(), GetPlotHeight() to get plot area size in pixels
- Pointf GetPosPrimary(double x, double y) 
  double GetSizeX(double cx) 		
  double GetSizeYPrimary(double cy) 	
  Pointf GetPosSecondary(double x, double y)
  double GetSizeYSecondary(double cy)
to get positions and sizes from plot units to pixel units.

	void OnPainter(Painter &w)		{OnPaint(w);}
	void OnDraw(Draw &w)			{OnPaint(w);}
	
	template <class T>
	void OnPaint(T& w) {
	...
 	}