This material demonstrates a very simple (and useless!) update script. The line thickness is changed based upon the distance between the point A and the line. The point thickness is changed based upon the distance to the x axis. This material is part of the [url=http://wiki.geogebra.org/en/Tutorial:Introduction_to_GeoGebraScript]Introduction to GeoGebraScript[/url] tutorial in the wiki, have a look at it if you're interested in scripting.