... Let the window respond to an undo manager event instead, whenever there
is a push or modify
Maybe this makes a few unnecessary redraws that did not happen before. If
that is important, then we should figure out how to put the logic for eliding
the redraw into ProjectWindow, and the extra information needed for the
decision into the events, but not make intrusions in other code all over the
place.
... It is const, renamed CopyTo, and invokes the create-on-demand factory in
the destination track; this means Track.cpp doesn't need to do that, and so
does not need TrackView.h
... non-intrusively in the Track suclasses, registering functions instead.
For each abstract factory function (of two), build a table of concrete factory
functions, paralleling the hierarchy of Track subclesses. Dispatch using
runt time type information in the Track objects.
... and eliminate some unnecessary calls to SubstitutePendingChangedTrack,
because the track and the substitute store Y and height in their shared
TrackView object.
Also make GetMinimizedHeight() virtual to avoid inclusion of TrackPanel.h in
TrackView.cpp.
... And Track no longer inherits TrackPanelCell, so be careful to rewrite
some dynamic_casts too to check instead for TrackView. Those casts won't fail
to recompile if not rewritten.
... in anticipation of making views to tracks many-to-one, but then the rulers
should be one-to-one with the views. So go through the view to get the ruler.
The ruler is really a left-hand extension for each view.
