how to get enum values from a list (webpart custom property)

Hi.

Title is all the question: in SharePoint 2010, it was possible to add code to set available values for an enum custom property (webpart). In SharePoint 2013, Visual Studio creates Elements.xml. How to load enum properties values from a sharepoint list?

Precision: the context is inside an app, including the list I would like to refer to. The aim is to give the possibilities to the user to customize the webpart. He creates data, loads it into a list and can use the list inside the app.