95     surfaces: BTreeMap<SurfaceId, Surface>,  field
102             surfaces: Default::default(),  in new()
110         self.surfaces.insert(new_surface_id, new_surface);  in create_surface()
117         SurfaceId::new(surface_id).and_then(move |id| self.surfaces.get_mut(&id))  in get_surface()
121         SurfaceId::new(surface_id).and_then(|id| self.surfaces.remove(&id));  in destroy_surface()
134     surfaces: SurfacesHelper,  field
143             surfaces: SurfacesHelper::new(),  in new()
160         Ok(self.surfaces.create_surface(width, height))  in create_surface()
164         self.surfaces.destroy_surface(surface_id);  in release_surface()
168         self.surfaces  in framebuffer()
178         self.surfaces.flip_surface(surface_id);  in flip()