simple example of drawing a spiral

draw a spiral, showing the mouse cursor position, and being able to zoom

Author	Example of http:/en.wikibooks.org/wiki/Gambas/Graphics and enlarged by Julio Sánchez Berro
License	GPL v2 or greater
URL	http:/sologambas.blogspot.com.es/2012/08/dibujo-de-una-espiral-zoom-y.html