In order to get started with GEF this pdf document is very helpful. It describes step by step how to create a project with the basic GEF functionalities showing screenshots of the application and all the code that is necessary. I recommend working through it before asking any questions. For those who want to save some time I will prepare a zip file containing the TutoGEF project.
At this point I want to thank Jean-Charles Mammana, Romain Meson and Jonathan Gramain for their work.
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