Hi Stef, In the section "Message structure" some of the code refers to the class Pen which is no longer in the default image (I think it is located in PharoExtras?), perhaps it would be better to change the examples to another class existing in the default image so one can easily try out the code? Best regards, Henrik -----Original Message----- From: Pharo-users [mailto:pharo-users-bounces@lists.pharo.org] On Behalf Of stepharo Sent: Sunday, January 24, 2016 10:17 PM To: Pharo Development List <pharo-dev@lists.pharo.org>; Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: [Pharo-users] 4th Chapter of Updated Pharo by Example ready for review. 4th Chapter of Updated Pharo by Example ready for review. https://ci.inria.fr/pharo-contribution/view/Books/job/UpdatedPharoByExample/... This one was way simpler than the PharoTour and FirstAplication, so I imagine that the review will be easier too. Stef Not thinking too much, just doing.