Monitors the _active_ views, i.e.
Monitors the _active_ views, i.e. views which are intersecting with the current transport position.
The view must store a handle to its underlying model.
The view must store a handle to its underlying model.
Returns the set of _active_ views, i.e.
Returns the set of _active_ views, i.e. views which are intersecting with the current transport position.