There were several architectural fixes needed:

1) KisAnimationCurveChannelListModel stores an internal list of
   selected nodes (dummies), therefore it should also be subscribed
   to sigBeginRemoveDummy() signal to update this list **before**
   the dummy will be actually deleted.

2) KisNodeManager should not allow activating a node if it is
   not visible in the layers docker (KisNodeModel). To move the
   "model" part of node hiding into KisNodeManager without making
   all the internal classes depend on it a special class
   KisNodeDisplayModeAdapter was introduced.

BUG:397809