Reading a caf::PdmPtrField sets the pointer to null before the reference string is resolved, and clearing a ptr field disconnects all signals between the referenced object and the field owner. The signal connections established by RimFilterInViewCollection::setSourceCollections() in the view constructor were therefore lost when a project was loaded, and adding a cell filter, property filter or data filter no longer refreshed the Filters node in the project tree. Reconnect in initAfterRead, which runs after the references have been resolved.
