This breaks a couple of views in Mockup (Gallery and SceneGallery). The idea of clearing the map instead of creating a new object was that if any view was listening to the scenes map object, it shouldn't re-register itself every time a new model is loaded (since the object changes). 

Retrospectively, I think that choice is somehow inconsistent with the rest of the model, and it's probably better that views register for LoadEvents instead. So, I am ok with this, but it'd be necessary to revise SceneGallery and Gallery.