change PropertyChange from a bitfield into a real object, with all the many widespread changes that causes

git-svn-id: svn://localhost/ardour2/branches/3.0@6701 d708f5d6-7413-0410-9779-e7cbd77b26cf

33 files changed, 358 insertions, 563 deletions

diff --git a/libs/ardour/ardour/ardour.h b/libs/ardour/ardour/ardour.h
index f608db5b7e..2b1f7bbb04 100644
--- a/libs/ardour/ardour/ardour.h
+++ b/libs/ardour/ardour/ardour.h
@@ -53,6 +53,9 @@ namespace ARDOUR {
 	void init_post_engine ();
 	int cleanup ();
 	bool no_auto_connect ();
+	void make_property_quarks ();
+
+	extern PBD::PropertyChange bounds_change;
 
 	std::string get_ardour_revision ();
 	extern const char* const ardour_config_info;
@@ -65,12 +68,6 @@ namespace ARDOUR {
 		return (microseconds_t) jack_get_time();
 	}
 
-	extern PBD::PropertyChange StartChanged;
-	extern PBD::PropertyChange LengthChanged;
-	extern PBD::PropertyChange PositionChanged;
-	extern PBD::PropertyChange NameChanged;
-	extern PBD::PropertyChange BoundsChanged;
-
 	static const double SHUTTLE_FRACT_SPEED1=0.48412291827; /* derived from A1,A2 */
 
 	void setup_fpu ();
diff --git a/libs/ardour/ardour/audioplaylist.h b/libs/ardour/ardour/audioplaylist.h
index b5df4cfabb..b53f3c1f73 100644
--- a/libs/ardour/ardour/audioplaylist.h
+++ b/libs/ardour/ardour/audioplaylist.h
@@ -79,8 +79,8 @@ class AudioPlaylist : public ARDOUR::Playlist
        XMLNode& state (bool full_state);
        void dump () const;
 
-       bool region_changed (PBD::PropertyChange, boost::shared_ptr<Region>);
-       void crossfade_changed (PBD::PropertyChange);
+       bool region_changed (const PBD::PropertyChange&, boost::shared_ptr<Region>);
+       void crossfade_changed (const PBD::PropertyChange&);
        void add_crossfade (boost::shared_ptr<Crossfade>);
 
        void source_offset_changed (boost::shared_ptr<AudioRegion> region);
diff --git a/libs/ardour/ardour/audioregion.h b/libs/ardour/ardour/audioregion.h
index 711c8030bd..ec9a64002f 100644
--- a/libs/ardour/ardour/audioregion.h
+++ b/libs/ardour/ardour/audioregion.h
@@ -44,6 +44,17 @@ namespace Properties {
 	extern PBD::PropertyDescriptor<bool> fade_in_active;
 	extern PBD::PropertyDescriptor<bool> fade_out_active;
 	extern PBD::PropertyDescriptor<float> scale_amplitude;
+	extern PBD::PropertyDescriptor<float> scale_amplitude;
+
+	/* the envelope and fades are not scalar items and so
+	   currently (2010/02) are not stored using Property.
+	   However, these descriptors enable us to notify
+	   about changes to them via PropertyChange.
+	*/
+
+	extern PBD::PropertyDescriptor<bool> envelope;
+	extern PBD::PropertyDescriptor<bool> fade_in;
+	extern PBD::PropertyDescriptor<bool> fade_out;
 }
 
 class Route;
@@ -58,14 +69,6 @@ class AudioRegion : public Region
   public:
 	static void make_property_quarks ();
 
-	static PBD::PropertyChange FadeInChanged;
-	static PBD::PropertyChange FadeOutChanged;
-	static PBD::PropertyChange FadeInActiveChanged;
-	static PBD::PropertyChange FadeOutActiveChanged;
-	static PBD::PropertyChange EnvelopeActiveChanged;
-	static PBD::PropertyChange ScaleAmplitudeChanged;
-	static PBD::PropertyChange EnvelopeChanged;
-
 	~AudioRegion();
 
 	void copy_settings (boost::shared_ptr<const AudioRegion>);
@@ -185,8 +188,7 @@ class AudioRegion : public Region
 	AudioRegion (const SourceList &);
 	AudioRegion (boost::shared_ptr<const AudioRegion>, frameoffset_t offset = 0, bool offset_relative = true);
 	AudioRegion (boost::shared_ptr<const AudioRegion>, const SourceList&);
-	AudioRegion (boost::shared_ptr<AudioSource>, const XMLNode&);
-	AudioRegion (SourceList &, const XMLNode&);
+	AudioRegion (SourceList &);
 
   private:
 	PBD::Property<bool>     _envelope_active;
@@ -197,7 +199,7 @@ class AudioRegion : public Region
 	PBD::Property<gain_t>   _scale_amplitude;
 	
 	void register_properties ();
-	PBD::PropertyChange set_property (const PBD::PropertyBase& prop);
+	bool set_property (const PBD::PropertyBase& prop);
 	void post_set ();
 
 	void init ();
diff --git a/libs/ardour/ardour/crossfade.h b/libs/ardour/ardour/crossfade.h
index 15b9b3d2a7..7b5ac28379 100644
--- a/libs/ardour/ardour/crossfade.h
+++ b/libs/ardour/ardour/crossfade.h
@@ -34,6 +34,11 @@
 #include "evoral/Curve.hpp"
 
 namespace ARDOUR {
+	namespace Properties {
+		/* "active" is defined elsewhere but we use it with crossfade also */
+		extern PBD::PropertyDescriptor<bool> active;
+		extern PBD::PropertyDescriptor<bool> follow_overlap;
+	}
 
 class AudioRegion;
 class Playlist;
@@ -71,6 +76,8 @@ class Crossfade : public ARDOUR::AudioRegion
 	Crossfade (const Playlist&, XMLNode&);
 	virtual ~Crossfade();
 
+	static void make_property_quarks ();
+
 	bool operator== (const ARDOUR::Crossfade&);
 
 	XMLNode& get_state (void);
@@ -106,7 +113,6 @@ class Crossfade : public ARDOUR::AudioRegion
 	framecnt_t overlap_length() const;
 
 	PBD::Signal1<void,boost::shared_ptr<Region> > Invalidated;
-	PBD::Signal1<void,PBD::PropertyChange>     StateChanged;
 
 	bool covers (framecnt_t frame) const {
 		return _position <= frame && frame < _position + _length;
@@ -136,9 +142,6 @@ class Crossfade : public ARDOUR::AudioRegion
 	static framecnt_t short_xfade_length() { return _short_xfade_length; }
 	static void set_short_xfade_length (framecnt_t n);
 
-	static PBD::PropertyChange ActiveChanged;
-	static PBD::PropertyChange FollowOverlapChanged;
-
   private:
 	friend struct CrossfadeComparePtr;
 	friend class AudioPlaylist;
@@ -147,11 +150,11 @@ class Crossfade : public ARDOUR::AudioRegion
 
 	boost::shared_ptr<ARDOUR::AudioRegion> _in;
 	boost::shared_ptr<ARDOUR::AudioRegion> _out;
-	bool                 _active;
+	PBD::Property<bool>  _active;
+	PBD::Property<bool>  _follow_overlap;
 	bool                 _in_update;
 	OverlapType           overlap_type;
 	AnchorPoint          _anchor_point;
-	bool                 _follow_overlap;
 	bool                 _fixed;
 	int32_t               layer_relation;
 
diff --git a/libs/ardour/ardour/diskstream.h b/libs/ardour/ardour/diskstream.h
index 90bcf4067a..48a9c2776b 100644
--- a/libs/ardour/ardour/diskstream.h
+++ b/libs/ardour/ardour/diskstream.h
@@ -206,7 +206,7 @@ class Diskstream : public SessionObject
 
 	/* XXX fix this redundancy ... */
 
-	virtual void playlist_changed (PBD::PropertyChange);
+	virtual void playlist_changed (const PBD::PropertyChange&);
 	virtual void playlist_deleted (boost::weak_ptr<Playlist>);
 	virtual void playlist_ranges_moved (std::list< Evoral::RangeMove<framepos_t> > const &);
 
diff --git a/libs/ardour/ardour/internal_send.h b/libs/ardour/ardour/internal_send.h
index 2171462ab7..243106fb54 100644
--- a/libs/ardour/ardour/internal_send.h
+++ b/libs/ardour/ardour/internal_send.h
@@ -56,7 +56,7 @@ class InternalSend : public Send
 	PBD::ScopedConnection connect_c;
 
 	void send_to_going_away ();
-	void send_to_name_changed ();
+	void send_to_property_changed (const PBD::PropertyChange&);
 	int  connect_when_legal ();
 	int  set_our_state (XMLNode const &, int);
 };
diff --git a/libs/ardour/ardour/location.h b/libs/ardour/ardour/location.h
index d93ffeec4a..938177b102 100644
--- a/libs/ardour/ardour/location.h
+++ b/libs/ardour/ardour/location.h
@@ -179,7 +179,7 @@ class Locations : public PBD::StatefulDestructible
 	PBD::Signal0<void>           changed;
 	PBD::Signal1<void,Location*> added;
 	PBD::Signal1<void,Location*> removed;
-	PBD::Signal1<void,PBD::PropertyChange>    StateChanged;
+	PBD::Signal1<void,const PBD::PropertyChange&>    StateChanged;
 
 	template<class T> void apply (T& obj, void (T::*method)(LocationList&)) {
 		Glib::Mutex::Lock lm (lock);
diff --git a/libs/ardour/ardour/midi_model.h b/libs/ardour/ardour/midi_model.h
index 77f5798898..fcd285f98c 100644
--- a/libs/ardour/ardour/midi_model.h
+++ b/libs/ardour/ardour/midi_model.h
@@ -90,7 +90,7 @@ public:
 	};
 
 
-	/** PropertyChange note properties.
+	/** Change note properties.
 	 * More efficient than DeltaCommand and has the important property that
 	 * it leaves the objects in the MidiModel (Notes) the same, thus
 	 * enabling selection and other state to persist across command
@@ -126,7 +126,7 @@ public:
 		boost::shared_ptr<MidiModel> _model;
 		const std::string            _name;
 
-		struct NotePropertyChange {
+		struct NoteChange {
 			DiffCommand::Property property;
 			boost::shared_ptr< Evoral::Note<TimeType> > note;
 			union {
@@ -139,11 +139,11 @@ public:
 			};
 		};
 
-		typedef std::list<NotePropertyChange> ChangeList;
+		typedef std::list<NoteChange> ChangeList;
 		ChangeList _changes;
 
-		XMLNode &marshal_change(const NotePropertyChange&);
-		NotePropertyChange unmarshal_change(XMLNode *xml_note);
+		XMLNode &marshal_change(const NoteChange&);
+		NoteChange unmarshal_change(XMLNode *xml_note);
 	};
 
 	MidiModel::DeltaCommand* new_delta_command(const std::string name="midi edit");
diff --git a/libs/ardour/ardour/midi_playlist.h b/libs/ardour/ardour/midi_playlist.h
index 46aea9f0b4..ccadb39e92 100644
--- a/libs/ardour/ardour/midi_playlist.h
+++ b/libs/ardour/ardour/midi_playlist.h
@@ -74,7 +74,7 @@ protected:
 private:
 	void dump () const;
 
-	bool region_changed (PBD::PropertyChange, boost::shared_ptr<Region>);
+	bool region_changed (const PBD::PropertyChange&, boost::shared_ptr<Region>);
 
 	NoteMode _note_mode;
 
diff --git a/libs/ardour/ardour/midi_region.h b/libs/ardour/ardour/midi_region.h
index d892e5837f..671e4fca43 100644
--- a/libs/ardour/ardour/midi_region.h
+++ b/libs/ardour/ardour/midi_region.h
@@ -96,11 +96,8 @@ class MidiRegion : public Region
   private:
 	friend class RegionFactory;
 
-	MidiRegion (boost::shared_ptr<MidiSource>);
 	MidiRegion (const SourceList&);
 	MidiRegion (boost::shared_ptr<const MidiRegion>, frameoffset_t offset = 0, bool offset_relative = true);
-	MidiRegion (boost::shared_ptr<MidiSource>, const XMLNode&);
-	MidiRegion (const SourceList &, const XMLNode&);
 
   private:
 	framecnt_t _read_at (const SourceList&, Evoral::EventSink<nframes_t>& dst,
diff --git a/libs/ardour/ardour/playlist.h b/libs/ardour/ardour/playlist.h
index 9cd02dec1e..7213c99397 100644
--- a/libs/ardour/ardour/playlist.h
+++ b/libs/ardour/ardour/playlist.h
@@ -249,15 +249,15 @@ class Playlist : public SessionObject
 	void notify_length_changed ();
 	void notify_layering_changed ();
 	void notify_contents_changed ();
-	void notify_state_changed (PBD::PropertyChange);
+	void notify_state_changed (const PBD::PropertyChange&);
 	void notify_region_moved (boost::shared_ptr<Region>);
 
 	void mark_session_dirty();
 
-	void region_changed_proxy (PBD::PropertyChange, boost::weak_ptr<Region>);
-	virtual bool region_changed (PBD::PropertyChange, boost::shared_ptr<Region>);
+	void region_changed_proxy (const PBD::PropertyChange&, boost::weak_ptr<Region>);
+	virtual bool region_changed (const PBD::PropertyChange&, boost::shared_ptr<Region>);
 
-	void region_bounds_changed (PBD::PropertyChange, boost::shared_ptr<Region>);
+	void region_bounds_changed (const PBD::PropertyChange&, boost::shared_ptr<Region>);
 	void region_deleted (boost::shared_ptr<Region>);
 
 	void sort_regions ();
diff --git a/libs/ardour/ardour/region.h b/libs/ardour/ardour/region.h
index 60ccf66984..fb827e308d 100644
--- a/libs/ardour/ardour/region.h
+++ b/libs/ardour/ardour/region.h
@@ -89,16 +89,7 @@ class Region
 		MusicTime
 	};
 
-	static PBD::PropertyChange FadeChanged;
-	static PBD::PropertyChange SyncOffsetChanged;
-	static PBD::PropertyChange MuteChanged;
-	static PBD::PropertyChange OpacityChanged;
-	static PBD::PropertyChange LockChanged;
-	static PBD::PropertyChange LayerChanged;
-	static PBD::PropertyChange HiddenChanged;
-
-	PBD::Signal1<void,PBD::PropertyChange> StateChanged;
-	static PBD::Signal1<void,boost::shared_ptr<ARDOUR::Region> > RegionPropertyChanged;
+	static PBD::Signal2<void,boost::shared_ptr<ARDOUR::Region>, const PBD::PropertyChange&> RegionPropertyChanged;
 
 	void unlock_property_changes () { _no_property_changes = false; }
 	void block_property_changes () { _no_property_changes = true; }
@@ -281,8 +272,6 @@ class Region
   protected:
 	friend class RegionFactory;
 
-	/** Construct a region from a single source */
-	Region (boost::shared_ptr<Source> src);
 	/** Construct a region from multiple sources*/
 	Region (const SourceList& srcs);
 	/** Construct a region from another region, at an offset within that region */
@@ -292,16 +281,11 @@ class Region
 	/** normal Region copy constructor */
 	Region (boost::shared_ptr<const Region>);
 
-	/** Construct a region from 1 source and XML state */
-	Region (boost::shared_ptr<Source> src, const XMLNode&);
-	/** Construct a region from multiple sources and XML state */
-	Region (const SourceList& srcs, const XMLNode&);
-
 	/** Constructor for derived types only */
 	Region (Session& s, framepos_t start, framecnt_t length, const std::string& name, DataType);
 
   protected:
-	void send_change (PBD::PropertyChange);
+	void send_change (const PBD::PropertyChange&);
 
 	void trim_to_internal (framepos_t position, framecnt_t length, void *src);
 	virtual void set_position_internal (framepos_t pos, bool allow_bbt_recompute);
@@ -351,7 +335,7 @@ class Region
 	AnalysisFeatureList     _transients;
 	bool                    _valid_transients;
 	mutable uint64_t        _read_data_count;  ///< modified in read()
-	PBD::PropertyChange             _pending_changed;
+	PBD::PropertyChange     _pending_changed;
 	uint64_t                _last_layer_op;  ///< timestamp
 	Glib::Mutex             _lock;
 	SourceList              _sources;
@@ -365,7 +349,7 @@ class Region
 
 	virtual int _set_state (const XMLNode&, int version, PBD::PropertyChange& what_changed, bool send_signal);
 
-	PBD::PropertyChange set_property (const PBD::PropertyBase&);
+	bool set_property (const PBD::PropertyBase&);
 	void register_properties ();
 
 private:
diff --git a/libs/ardour/ardour/route_group.h b/libs/ardour/ardour/route_group.h
index 820295b54a..f3109a707d 100644
--- a/libs/ardour/ardour/route_group.h
+++ b/libs/ardour/ardour/route_group.h
@@ -131,9 +131,6 @@ class RouteGroup : public SessionObject
 	PBD::Signal0<void> changed;
 	PBD::Signal1<void,void*> FlagsChanged;
 
-	static PBD::PropertyChange FlagsChange;
-	static PBD::PropertyChange PropertiesChange;
-
 	XMLNode& get_state ();
 	
 	int set_state (const XMLNode&, int version);
diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 154c5d0078..9294d56fcc 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -1210,7 +1210,7 @@ class Session : public PBD::StatefulDestructible, public PBD::ScopedConnectionLi
 	void xrun_recovery ();
 
 	TempoMap    *_tempo_map;
-	void          tempo_map_changed (PBD::PropertyChange);
+	void          tempo_map_changed (const PBD::PropertyChange&);
 
 	/* edit/mix groups */
 
@@ -1257,7 +1257,7 @@ class Session : public PBD::StatefulDestructible, public PBD::ScopedConnectionLi
 	RegionList regions;
 
 	void add_region (boost::shared_ptr<Region>);
-	void region_changed (PBD::PropertyChange, boost::weak_ptr<Region>);
+	void region_changed (const PBD::PropertyChange&, boost::weak_ptr<Region>);
 	void remove_region (boost::weak_ptr<Region>);
 
 	int load_regions (const XMLNode& node);
diff --git a/libs/ardour/ardour/session_object.h b/libs/ardour/ardour/session_object.h
index 1f81cf6fd2..d18a1f9d41 100644
--- a/libs/ardour/ardour/session_object.h
+++ b/libs/ardour/ardour/session_object.h
@@ -48,7 +48,7 @@ class SessionObject : public SessionHandleRef, public PBD::StatefulDestructible
 
 	SessionObject (Session& session, const std::string& name)
 		: SessionHandleRef (session)
-		, _name (Properties::name, PBD::PropertyChange (0), name)
+		, _name (Properties::name, name)
 	{
 		add_property (_name);
 	}
@@ -56,18 +56,16 @@ class SessionObject : public SessionHandleRef, public PBD::StatefulDestructible
 	Session&    session() const { return _session; }
 	std::string name()    const { return _name; }
 
-	PBD::PropertyChange set_property (const PBD::PropertyBase& prop);
+	bool set_property (const PBD::PropertyBase& prop);
 
 	virtual bool set_name (const std::string& str) {
 		if (_name != str) {
 			_name = str;
-			NameChanged();
+			PropertyChanged (PBD::PropertyChange (Properties::name));
 		}
 		return true;
 	}
 
-	PBD::Signal0<void> NameChanged;
-
   protected:
 	PBD::Property<std::string> _name;
 };
diff --git a/libs/ardour/ardour/tempo.h b/libs/ardour/ardour/tempo.h
index 5c2d3d6918..596444173f 100644
--- a/libs/ardour/ardour/tempo.h
+++ b/libs/ardour/ardour/tempo.h
@@ -258,8 +258,6 @@ class TempoMap : public PBD::StatefulDestructible
 
 	nframes_t frame_rate () const { return _frame_rate; }
 
-	PBD::Signal1<void,PBD::PropertyChange> StateChanged;
-
   private:
 	static Tempo    _default_tempo;
 	static Meter    _default_meter;
diff --git a/libs/ardour/audio_playlist.cc b/libs/ardour/audio_playlist.cc
index 60c7d4bdc3..6e8b35a072 100644
--- a/libs/ardour/audio_playlist.cc
+++ b/libs/ardour/audio_playlist.cc
@@ -525,7 +525,7 @@ AudioPlaylist::add_crossfade (boost::shared_ptr<Crossfade> xfade)
 		_crossfades.push_back (xfade);
 
 		xfade->Invalidated.connect_same_thread (*this, boost::bind (&AudioPlaylist::crossfade_invalidated, this, _1));
-		xfade->StateChanged.connect_same_thread (*this, boost::bind (&AudioPlaylist::crossfade_changed, this, _1));
+		xfade->PropertyChanged.connect_same_thread (*this, boost::bind (&AudioPlaylist::crossfade_changed, this, _1));
 
 		notify_crossfade_added (xfade);
 	}
@@ -581,7 +581,7 @@ AudioPlaylist::set_state (const XMLNode& node, int version)
 			boost::shared_ptr<Crossfade> xfade = boost::shared_ptr<Crossfade> (new Crossfade (*((const Playlist *)this), *child));
 			_crossfades.push_back (xfade);
 			xfade->Invalidated.connect_same_thread (*this, boost::bind (&AudioPlaylist::crossfade_invalidated, this, _1));
-			xfade->StateChanged.connect_same_thread (*this, boost::bind (&AudioPlaylist::crossfade_changed, this, _1));
+			xfade->PropertyChanged.connect_same_thread (*this, boost::bind (&AudioPlaylist::crossfade_changed, this, _1));
 			NewCrossfade(xfade);
 		}
 
@@ -726,7 +726,7 @@ AudioPlaylist::destroy_region (boost::shared_ptr<Region> region)
 }
 
 void
-AudioPlaylist::crossfade_changed (PropertyChange)
+AudioPlaylist::crossfade_changed (const PropertyChange&)
 {
 	if (in_flush || in_set_state) {
 		return;
@@ -742,24 +742,27 @@ AudioPlaylist::crossfade_changed (PropertyChange)
 }
 
 bool
-AudioPlaylist::region_changed (PropertyChange what_changed, boost::shared_ptr<Region> region)
+AudioPlaylist::region_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
 {
 	if (in_flush || in_set_state) {
 		return false;
 	}
 
-	PropertyChange our_interests = PropertyChange (AudioRegion::FadeInChanged|
-				       AudioRegion::FadeOutChanged|
-				       AudioRegion::FadeInActiveChanged|
-				       AudioRegion::FadeOutActiveChanged|
-				       AudioRegion::EnvelopeActiveChanged|
-				       AudioRegion::ScaleAmplitudeChanged|
-				       AudioRegion::EnvelopeChanged);
+	PropertyChange our_interests;
+
+	our_interests.add (Properties::fade_in_active);
+	our_interests.add (Properties::fade_out_active);
+	our_interests.add (Properties::scale_amplitude);
+	our_interests.add (Properties::envelope_active);
+	our_interests.add (Properties::envelope);
+	our_interests.add (Properties::fade_in);
+	our_interests.add (Properties::fade_out);
+
 	bool parent_wants_notify;
 
 	parent_wants_notify = Playlist::region_changed (what_changed, region);
 
-	if ((parent_wants_notify || (what_changed & our_interests))) {
+	if (parent_wants_notify || (what_changed.contains (our_interests))) {
 		notify_contents_changed ();
 	}
 
diff --git a/libs/ardour/audioregion.cc b/libs/ardour/audioregion.cc
index f1af3b6fab..21fda237cb 100644
--- a/libs/ardour/audioregion.cc
+++ b/libs/ardour/audioregion.cc
@@ -89,12 +89,12 @@ AudioRegion::register_properties ()
 }
 
 #define AUDIOREGION_STATE_DEFAULT \
-	_envelope_active (Properties::envelope_active, EnvelopeActiveChanged, false) \
-	, _default_fade_in (Properties::default_fade_in, FadeInChanged, true) \
-	, _default_fade_out (Properties::default_fade_out, FadeOutChanged, true) \
-	, _fade_in_active (Properties::fade_in_active, FadeInActiveChanged, true) \
-	, _fade_out_active (Properties::fade_out_active, FadeOutActiveChanged, true) \
-	, _scale_amplitude (Properties::scale_amplitude, ScaleAmplitudeChanged, 1.0)
+	_envelope_active (Properties::envelope_active, false) \
+	, _default_fade_in (Properties::default_fade_in, true) \
+	, _default_fade_out (Properties::default_fade_out, true) \
+	, _fade_in_active (Properties::fade_in_active, true) \
+	, _fade_out_active (Properties::fade_out_active, true) \
+	, _scale_amplitude (Properties::scale_amplitude, 0.0)
 
 #define AUDIOREGION_COPY_STATE(other) \
 	 _envelope_active (other->_envelope_active) \
@@ -104,14 +104,6 @@ AudioRegion::register_properties ()
         , _fade_out_active (other->_fade_out_active) \
 	, _scale_amplitude (other->_scale_amplitude) 
 
-PropertyChange AudioRegion::FadeInChanged         = PBD::new_change();
-PropertyChange AudioRegion::FadeOutChanged        = PBD::new_change();
-PropertyChange AudioRegion::FadeInActiveChanged   = PBD::new_change();
-PropertyChange AudioRegion::FadeOutActiveChanged  = PBD::new_change();
-PropertyChange AudioRegion::EnvelopeActiveChanged = PBD::new_change();
-PropertyChange AudioRegion::ScaleAmplitudeChanged = PBD::new_change();
-PropertyChange AudioRegion::EnvelopeChanged       = PBD::new_change();
-
 /* a Session will reset these to its chosen defaults by calling AudioRegion::set_default_fade() */
 
 void
@@ -142,26 +134,7 @@ AudioRegion::AudioRegion (Session& s, framepos_t start, framecnt_t len, std::str
 	assert (_sources.size() == _master_sources.size());
 }
 
-/** Basic AudioRegion constructor (one channel) */
-AudioRegion::AudioRegion (boost::shared_ptr<AudioSource> src)
-	: Region (boost::static_pointer_cast<Source>(src))
-	, AUDIOREGION_STATE_DEFAULT
-	, _automatable(src->session())
-	, _fade_in (new AutomationList(Evoral::Parameter(FadeInAutomation)))
-	, _fade_out (new AutomationList(Evoral::Parameter(FadeOutAutomation)))
-	, _envelope (new AutomationList(Evoral::Parameter(EnvelopeAutomation)))
-	, _fade_in_suspended (0)
-	, _fade_out_suspended (0)
-{
-	init ();
-	
-	/* XXX why is this set here ? - set in a property list given to RegionFactory */
-	_external = true;
-
-	assert (_sources.size() == _master_sources.size());
-}
-
-/** Basic AudioRegion constructor (many channels) */
+/** Basic AudioRegion constructor */
 AudioRegion::AudioRegion (const SourceList& srcs)
 	: Region (srcs)
 	, AUDIOREGION_STATE_DEFAULT
@@ -219,26 +192,8 @@ AudioRegion::AudioRegion (boost::shared_ptr<const AudioRegion> other, const Sour
 	assert (_sources.size() == _master_sources.size());
 }
 
-AudioRegion::AudioRegion (boost::shared_ptr<AudioSource> src, const XMLNode& node)
-	: Region (src, node)
-	, AUDIOREGION_STATE_DEFAULT
-	, _automatable(src->session())
-	, _fade_in (new AutomationList(Evoral::Parameter(FadeInAutomation)))
-	, _fade_out (new AutomationList(Evoral::Parameter(FadeOutAutomation)))
-	, _envelope (new AutomationList(Evoral::Parameter(EnvelopeAutomation)))
-{
-	init ();
-
-	if (set_state (node, Stateful::loading_state_version)) {
-		throw failed_constructor();
-	}
-
-	assert(_type == DataType::AUDIO);
-	assert (_sources.size() == _master_sources.size());
-}
-
-AudioRegion::AudioRegion (SourceList& srcs, const XMLNode& node)
-	: Region (srcs, node)
+AudioRegion::AudioRegion (SourceList& srcs)
+	: Region (srcs)
 	, AUDIOREGION_STATE_DEFAULT
 	, _automatable(srcs[0]->session())
 	, _fade_in (new AutomationList(Evoral::Parameter(FadeInAutomation)))
@@ -249,12 +204,7 @@ AudioRegion::AudioRegion (SourceList& srcs, const XMLNode& node)
 {
 	init ();
 
-	if (set_state (node, Stateful::loading_state_version)) {
-		throw failed_constructor();
-	}
-
 	assert(_type == DataType::AUDIO);
-	connect_to_analysis_changed ();
 	assert (_sources.size() == _master_sources.size());
 }
 
@@ -327,7 +277,7 @@ AudioRegion::set_envelope_active (bool yn)
 {
 	if (envelope_active() != yn) {
 		_envelope_active = yn;
-		send_change (EnvelopeActiveChanged);
+		send_change (PropertyChange (Properties::envelope_active));
 	}
 }
 
@@ -650,8 +600,7 @@ AudioRegion::_set_state (const XMLNode& node, int version, PropertyChange& what_
 		float a = atof (prop->value().c_str());
 		if (a != _scale_amplitude) {
 			_scale_amplitude = a;
-			what_changed = PropertyChange (what_changed|ScaleAmplitudeChanged);
-			cerr << _name << " amp changed\n";
+			what_changed.add (Properties::scale_amplitude);
 		}
 	}
 
@@ -730,7 +679,6 @@ AudioRegion::_set_state (const XMLNode& node, int version, PropertyChange& what_
 	thaw ();
 
 	if (send) {
-		cerr << _name << ": audio final change: " << hex << what_changed << dec << endl;
 		send_change (what_changed);
 	}
 
@@ -741,54 +689,52 @@ AudioRegion::_set_state (const XMLNode& node, int version, PropertyChange& what_
 	return 0;
 }
 
-PropertyChange
+bool
 AudioRegion::set_property (const PropertyBase& prop)
 {
-	PropertyChange c = PropertyChange (0);
-
 	DEBUG_TRACE (DEBUG::Properties,  string_compose ("audio region %1 set property %2\n", _name.val(), prop.property_name()));
 
 	if (prop == Properties::envelope_active.id) {
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
 		if (val != _envelope_active) {
 			_envelope_active = val;
-			c = EnvelopeActiveChanged;
+			return true;
 		}
 	} else if (prop == Properties::default_fade_in.id) {
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
 		if (val != _default_fade_in) {
 			_default_fade_in = val;
-			c = FadeInChanged;
+			return true;
 		}
 	} else if (prop == Properties::default_fade_out.id) {
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
 		if (val != _default_fade_out) {
 			_default_fade_out = val;
-			c = FadeOutChanged;
+			return true;
 		}
 	} else if (prop == Properties::fade_in_active.id) {
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
 		if (val != _fade_in_active) {
 			_fade_in_active = val;
-			c = FadeInActiveChanged;
+			return true;
 		}
 	} else if (prop == Properties::fade_out_active.id) {
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
 		if (val != _fade_out_active) {
 			_fade_out_active = val;
-			c = FadeOutChanged;
+			return true;
 		}
 	} else if (prop == Properties::scale_amplitude.id) {
 		gain_t val = dynamic_cast<const PropertyTemplate<gain_t>*>(&prop)->val();
 		if (val != _scale_amplitude) {
 			_scale_amplitude = val;
-			c = ScaleAmplitudeChanged;
+			return true;
 		}
 	} else {
 		return Region::set_property (prop);
 	}
-
-	return c;
+	
+	return false;
 }
 
 int
@@ -817,7 +763,7 @@ AudioRegion::set_fade_in (boost::shared_ptr<AutomationList> f)
 	*_fade_in = *f;
 	_fade_in->thaw ();
 	
-	send_change (FadeInChanged);
+	send_change (PropertyChange (Properties::fade_in));
 }
 
 void
@@ -884,7 +830,7 @@ AudioRegion::set_fade_out (boost::shared_ptr<AutomationList> f)
 	*_fade_out = *f;
 	_fade_out->thaw ();
 
-	send_change (FadeInChanged);
+	send_change (PropertyChange (Properties::fade_in));
 }
 
 void
@@ -953,7 +899,7 @@ AudioRegion::set_fade_in_length (framecnt_t len)
 
 	if (changed) {
 		_default_fade_in = false;
-		send_change (FadeInChanged);
+		send_change (PropertyChange (Properties::fade_in));
 	}
 }
 
@@ -968,7 +914,7 @@ AudioRegion::set_fade_out_length (framecnt_t len)
 
 	if (changed) {
 		_default_fade_out = false;
-		send_change (FadeOutChanged);
+		send_change (PropertyChange (Properties::fade_out));
 	}
 }
 
@@ -980,7 +926,7 @@ AudioRegion::set_fade_in_active (bool yn)
 	}
 
 	_fade_in_active = yn;
-	send_change (FadeInActiveChanged);
+	send_change (PropertyChange (Properties::fade_in_active));
 }
 
 void
@@ -990,7 +936,7 @@ AudioRegion::set_fade_out_active (bool yn)
 		return;
 	}
 	_fade_out_active = yn;
-	send_change (FadeOutActiveChanged);
+	send_change (PropertyChange (Properties::fade_out_active));
 }
 
 bool
@@ -1050,12 +996,12 @@ AudioRegion::recompute_at_end ()
 
 	if (_fade_in->back()->when > _length) {
 		_fade_in->extend_to (_length);
-		send_change (FadeInChanged);
+		send_change (PropertyChange (Properties::fade_in));
 	}
 
 	if (_fade_out->back()->when > _length) {
 		_fade_out->extend_to (_length);
-		send_change (FadeOutChanged);
+		send_change (PropertyChange (Properties::fade_out));
 	}
 }
 
@@ -1068,12 +1014,12 @@ AudioRegion::recompute_at_start ()
 
 	if (_fade_in->back()->when > _length) {
 		_fade_in->extend_to (_length);
-		send_change (FadeInChanged);
+		send_change (PropertyChange (Properties::fade_in));
 	}
 
 	if (_fade_out->back()->when > _length) {
 		_fade_out->extend_to (_length);
-		send_change (FadeOutChanged);
+		send_change (PropertyChange (Properties::fade_out));
 	}
 }
 
@@ -1212,7 +1158,7 @@ AudioRegion::set_scale_amplitude (gain_t g)
 
 	/* tell everybody else */
 
-	send_change (ScaleAmplitudeChanged);
+	send_change (PropertyChange (Properties::scale_amplitude));
 }
 
 void
@@ -1282,25 +1228,25 @@ AudioRegion::normalize_to (float target_dB)
 
 	/* tell everybody else */
 
-	send_change (ScaleAmplitudeChanged);
+	send_change (PropertyChange (Properties::scale_amplitude));
 }
 
 void
 AudioRegion::fade_in_changed ()
 {
-	send_change (FadeInChanged);
+	send_change (PropertyChange (Properties::fade_in));
 }
 
 void
 AudioRegion::fade_out_changed ()
 {
-	send_change (FadeOutChanged);
+	send_change (PropertyChange (Properties::fade_out));
 }
 
 void
 AudioRegion::envelope_changed ()
 {
-	send_change (EnvelopeChanged);
+	send_change (PropertyChange (Properties::envelope));
 }
 
 void
diff --git a/libs/ardour/crossfade.cc b/libs/ardour/crossfade.cc
index dc84352f4e..8275876fe8 100644
--- a/libs/ardour/crossfade.cc
+++ b/libs/ardour/crossfade.cc
@@ -37,8 +37,6 @@ using namespace ARDOUR;
 using namespace PBD;
 
 framecnt_t Crossfade::_short_xfade_length = 0;
-PropertyChange Crossfade::ActiveChanged = new_change();
-PropertyChange Crossfade::FollowOverlapChanged = new_change();
 
 /* XXX if and when we ever implement parallel processing of the process()
    callback, these will need to be handled on a per-thread basis.
@@ -47,6 +45,24 @@ PropertyChange Crossfade::FollowOverlapChanged = new_change();
 Sample* Crossfade::crossfade_buffer_out = 0;
 Sample* Crossfade::crossfade_buffer_in = 0;
 
+
+#define CROSSFADE_DEFAULT_PROPERTIES \
+	_active (Properties::active, _session.config.get_xfades_active ()) \
+	, _follow_overlap (Properties::follow_overlap, false)
+
+
+namespace ARDOUR {
+	namespace Properties {
+		PropertyDescriptor<bool> follow_overlap;
+	}
+}
+
+void
+Crossfade::make_property_quarks ()
+{
+	Properties::follow_overlap.id = g_quark_from_static_string (X_("follow-overlap"));
+}
+
 void
 Crossfade::set_buffer_size (framecnt_t sz)
 {
@@ -72,26 +88,25 @@ Crossfade::Crossfade (boost::shared_ptr<AudioRegion> in, boost::shared_ptr<Audio
 		      framecnt_t length,
 		      framepos_t position,
 		      AnchorPoint ap)
-	: AudioRegion (in->session(), position, length, in->name() + string ("<>") + out->name()),
-	  _fade_in (Evoral::Parameter(FadeInAutomation)), // linear (gain coefficient) => -inf..+6dB
-	  _fade_out (Evoral::Parameter(FadeOutAutomation)) // linear (gain coefficient) => -inf..+6dB
+	: AudioRegion (in->session(), position, length, in->name() + string ("<>") + out->name())
+	, CROSSFADE_DEFAULT_PROPERTIES
+	, _fade_in (Evoral::Parameter(FadeInAutomation)) // linear (gain coefficient) => -inf..+6dB
+	, _fade_out (Evoral::Parameter(FadeOutAutomation)) // linear (gain coefficient) => -inf..+6dB
 
 {
 	_in = in;
 	_out = out;
 	_anchor_point = ap;
-	_follow_overlap = false;
-
-	_active = _session.config.get_xfades_active ();
 	_fixed = true;
 
 	initialize ();
 }
 
 Crossfade::Crossfade (boost::shared_ptr<AudioRegion> a, boost::shared_ptr<AudioRegion> b, CrossfadeModel model, bool act)
-	: AudioRegion (a->session(), 0, 0, a->name() + string ("<>") + b->name()),
-	  _fade_in (Evoral::Parameter(FadeInAutomation)), // linear (gain coefficient) => -inf..+6dB
-	  _fade_out (Evoral::Parameter(FadeOutAutomation)) // linear (gain coefficient) => -inf..+6dB
+	: AudioRegion (a->session(), 0, 0, a->name() + string ("<>") + b->name())
+	, CROSSFADE_DEFAULT_PROPERTIES
+	, _fade_in (Evoral::Parameter(FadeInAutomation)) // linear (gain coefficient) => -inf..+6dB
+	, _fade_out (Evoral::Parameter(FadeOutAutomation)) // linear (gain coefficient) => -inf..+6dB
 {
 	_in_update = false;
 	_fixed = false;
@@ -107,9 +122,10 @@ Crossfade::Crossfade (boost::shared_ptr<AudioRegion> a, boost::shared_ptr<AudioR
 }
 
 Crossfade::Crossfade (const Playlist& playlist, XMLNode& node)
-	: AudioRegion (playlist.session(), 0, 0, "unnamed crossfade"),
-	  _fade_in (Evoral::Parameter(FadeInAutomation)), // linear (gain coefficient) => -inf..+6dB
-	  _fade_out (Evoral::Parameter(FadeOutAutomation)) // linear (gain coefficient) => -inf..+6dB
+	: AudioRegion (playlist.session(), 0, 0, "unnamed crossfade")
+	, CROSSFADE_DEFAULT_PROPERTIES
+	, _fade_in (Evoral::Parameter(FadeInAutomation)) // linear (gain coefficient) => -inf..+6dB
+	, _fade_out (Evoral::Parameter(FadeOutAutomation)) // linear (gain coefficient) => -inf..+6dB
 
 {
 	boost::shared_ptr<Region> r;
@@ -163,6 +179,7 @@ Crossfade::Crossfade (const Playlist& playlist, XMLNode& node)
 
 Crossfade::Crossfade (boost::shared_ptr<Crossfade> orig, boost::shared_ptr<AudioRegion> newin, boost::shared_ptr<AudioRegion> newout)
 	: AudioRegion (boost::dynamic_pointer_cast<const AudioRegion> (orig), 0, true)
+	, CROSSFADE_DEFAULT_PROPERTIES
 	, _fade_in (orig->_fade_in)
 	, _fade_out (orig->_fade_out)
 {
@@ -377,7 +394,7 @@ Crossfade::set_active (bool yn)
 {
 	if (_active != yn) {
 		_active = yn;
-		StateChanged (ActiveChanged);
+		PropertyChanged (PropertyChange (Properties::active));
 	}
 }
 
@@ -442,7 +459,11 @@ Crossfade::refresh ()
 	}
 
 	if (send_signal) {
-		StateChanged (BoundsChanged); /* EMIT SIGNAL */
+		PropertyChange bounds;
+		bounds.add (Properties::start);
+		bounds.add (Properties::position);
+		bounds.add (Properties::length);
+		PropertyChanged (bounds); /* EMIT SIGNAL */
 	}
 
 	_in_update = false;
@@ -722,14 +743,14 @@ Crossfade::set_state (const XMLNode& node, int /*version*/)
 	XMLNode* fo;
 	const XMLProperty* prop;
 	LocaleGuard lg (X_("POSIX"));
-	PropertyChange what_changed = PropertyChange (0);
+	PropertyChange what_changed;
 	framepos_t val;
 
 	if ((prop = node.property ("position")) != 0) {
 		sscanf (prop->value().c_str(), "%" PRId64, &val);
 		if (val != _position) {
 			_position = val;
-			what_changed = PropertyChange (what_changed | PositionChanged);
+			what_changed.add (Properties::position);
 		}
 	} else {
 		warning << _("old-style crossfade information - no position information") << endmsg;
@@ -740,7 +761,7 @@ Crossfade::set_state (const XMLNode& node, int /*version*/)
 		bool x = string_is_affirmative (prop->value());
 		if (x != _active) {
 			_active = x;
-			what_changed = PropertyChange (what_changed | ActiveChanged);
+			what_changed.add (Properties::active);
 		}
 	} else {
 		_active = true;
@@ -769,7 +790,7 @@ Crossfade::set_state (const XMLNode& node, int /*version*/)
 		sscanf (prop->value().c_str(), "%" PRId64, &val);
 		if (val != _length) {
 			_length = val;
-			what_changed = PropertyChange (what_changed | LengthChanged);
+			what_changed.add (Properties::length);
 		}
 
 	} else {
@@ -840,7 +861,7 @@ Crossfade::set_state (const XMLNode& node, int /*version*/)
 
 	_fade_out.thaw ();
 
-	StateChanged (what_changed); /* EMIT SIGNAL */
+	PropertyChanged (what_changed); /* EMIT SIGNAL */
 
 	return 0;
 }
@@ -866,7 +887,7 @@ Crossfade::set_follow_overlap (bool yn)
 		set_xfade_length (_out->first_frame() + _out->length() - _in->first_frame());
 	}
 
-	StateChanged (FollowOverlapChanged);
+	PropertyChanged (PropertyChange (Properties::follow_overlap));
 }
 
 framecnt_t
@@ -900,8 +921,8 @@ Crossfade::set_xfade_length (framecnt_t len)
 
 	_length = len;
 
-	StateChanged (LengthChanged);
-
+	PropertyChanged (PropertyChange (Properties::length));
+	
 	return len;
 }
 
diff --git a/libs/ardour/diskstream.cc b/libs/ardour/diskstream.cc
index 6aee3a7572..f80eb849ec 100644
--- a/libs/ardour/diskstream.cc
+++ b/libs/ardour/diskstream.cc
@@ -361,7 +361,7 @@ Diskstream::use_playlist (boost::shared_ptr<Playlist> playlist)
 }
 
 void
-Diskstream::playlist_changed (PropertyChange)
+Diskstream::playlist_changed (const PropertyChange&)
 {
 	playlist_modified ();
 }
diff --git a/libs/ardour/globals.cc b/libs/ardour/globals.cc
index f117e6d063..ee19f1caac 100644
--- a/libs/ardour/globals.cc
+++ b/libs/ardour/globals.cc
@@ -102,12 +102,6 @@ MIDI::Port *ARDOUR::default_mtc_port = 0;
 MIDI::Port *ARDOUR::default_midi_port = 0;
 MIDI::Port *ARDOUR::default_midi_clock_port = 0;
 
-PropertyChange ARDOUR::StartChanged = PBD::new_change ();
-PropertyChange ARDOUR::LengthChanged = PBD::new_change ();
-PropertyChange ARDOUR::PositionChanged = PBD::new_change ();
-PropertyChange ARDOUR::NameChanged = PBD::new_change ();
-PropertyChange ARDOUR::BoundsChanged = PropertyChange (0); // see init(), below
-
 compute_peak_t          ARDOUR::compute_peak = 0;
 find_peaks_t            ARDOUR::find_peaks = 0;
 apply_gain_to_buffer_t  ARDOUR::apply_gain_to_buffer = 0;
@@ -118,6 +112,36 @@ PBD::Signal1<void,std::string> ARDOUR::BootMessage;
 
 void ARDOUR::setup_enum_writer ();
 
+/* this is useful for quite a few things that want to check
+   if any bounds-related property has changed
+*/
+PBD::PropertyChange ARDOUR::bounds_change;
+
+namespace ARDOUR { 
+	namespace Properties {
+
+		/* the envelope and fades are not scalar items and so
+		   currently (2010/02) are not stored using Property.
+		   However, these descriptors enable us to notify
+		   about changes to them via PropertyChange. 
+
+		   Declared in ardour/audioregion.h ...
+		*/
+
+		PBD::PropertyDescriptor<bool> fade_in;
+		PBD::PropertyDescriptor<bool> fade_out;
+		PBD::PropertyDescriptor<bool> envelope;
+	}
+}
+
+void
+ARDOUR::make_property_quarks ()
+{
+	Properties::fade_in.id = g_quark_from_static_string (X_("fade_in_FAKE"));
+	Properties::fade_out.id = g_quark_from_static_string (X_("fade_out_FAKE"));
+	Properties::envelope.id = g_quark_from_static_string (X_("envelope_FAKE"));
+}
+
 int
 ARDOUR::setup_midi ()
 {
@@ -302,12 +326,23 @@ ARDOUR::init (bool use_vst, bool try_optimization)
 
 	PBD::ID::init ();
 	SessionEvent::init_event_pool ();
-
+	
+	make_property_quarks ();
 	SessionObject::make_property_quarks ();
 	Region::make_property_quarks ();
 	AudioRegion::make_property_quarks ();
 	RouteGroup::make_property_quarks ();
 
+	/* this is a useful ready to use PropertyChange that many
+	   things need to check. This avoids having to compose
+	   it every time we want to check for any of the relevant
+	   property changes.
+	*/
+
+	bounds_change.add (ARDOUR::Properties::start);
+	bounds_change.add (ARDOUR::Properties::position);
+	bounds_change.add (ARDOUR::Properties::length);
+
 	/* provide a state version for the few cases that need it and are not
 	   driven by reading state from disk (e.g. undo/redo)
 	*/
@@ -367,8 +402,6 @@ ARDOUR::init (bool use_vst, bool try_optimization)
 	/* singleton - first object is "it" */
 	new PluginManager ();
 
-	BoundsChanged = PropertyChange (StartChanged|PositionChanged|LengthChanged);
-
 	return 0;
 }
 
diff --git a/libs/ardour/internal_send.cc b/libs/ardour/internal_send.cc
index 4a4823a29f..5944677934 100644
--- a/libs/ardour/internal_send.cc
+++ b/libs/ardour/internal_send.cc
@@ -44,7 +44,7 @@ InternalSend::InternalSend (Session& s, boost::shared_ptr<MuteMaster> mm, boost:
 	set_name (sendto->name());
 
 	_send_to->DropReferences.connect_same_thread (*this, boost::bind (&InternalSend::send_to_going_away, this));
-	_send_to->NameChanged.connect_same_thread (*this, boost::bind (&InternalSend::send_to_name_changed, this));
+	_send_to->PropertyChanged.connect_same_thread (*this, boost::bind (&InternalSend::send_to_property_changed, this, _1));;
 }
 
 InternalSend::InternalSend (Session& s, boost::shared_ptr<MuteMaster> mm, const XMLNode& node)
@@ -269,7 +269,9 @@ InternalSend::visible () const
 }
 
 void
-InternalSend::send_to_name_changed ()
+InternalSend::send_to_property_changed (const PropertyChange& what_changed)
 {
-	set_name (_send_to->name ());
+	if (what_changed.contains (Properties::name)) {
+		set_name (_send_to->name ());
+	}
 }
diff --git a/libs/ardour/midi_model.cc b/libs/ardour/midi_model.cc
index baa3c2c7c0..ac3360ea2b 100644
--- a/libs/ardour/midi_model.cc
+++ b/libs/ardour/midi_model.cc
@@ -326,7 +326,7 @@ void
 MidiModel::DiffCommand::change(const boost::shared_ptr< Evoral::Note<TimeType> > note, Property prop,
 			       uint8_t new_value)
 {
-	NotePropertyChange change;
+	NoteChange change;
 
 	change.note = note;
 	change.property = prop;
@@ -359,7 +359,7 @@ void
 MidiModel::DiffCommand::change(const boost::shared_ptr< Evoral::Note<TimeType> > note, Property prop,
 			       TimeType new_time)
 {
-	NotePropertyChange change;
+	NoteChange change;
 
 	change.note = note;
 	change.property = prop;
@@ -443,7 +443,7 @@ MidiModel::DiffCommand::undo()
 }
 
 XMLNode&
-MidiModel::DiffCommand::marshal_change(const NotePropertyChange& change)
+MidiModel::DiffCommand::marshal_change(const NoteChange& change)
 {
 	XMLNode* xml_change = new XMLNode("change");
 
@@ -516,11 +516,11 @@ MidiModel::DiffCommand::marshal_change(const NotePropertyChange& change)
 	return *xml_change;
 }
 
-MidiModel::DiffCommand::NotePropertyChange
+MidiModel::DiffCommand::NoteChange
 MidiModel::DiffCommand::unmarshal_change(XMLNode *xml_change)
 {
 	XMLProperty* prop;
-	NotePropertyChange change;
+	NoteChange change;
 	unsigned int note;
 	unsigned int channel;
 	unsigned int velocity;
diff --git a/libs/ardour/midi_playlist.cc b/libs/ardour/midi_playlist.cc
index cafbcc9e93..8c94bb1a7f 100644
--- a/libs/ardour/midi_playlist.cc
+++ b/libs/ardour/midi_playlist.cc
@@ -415,7 +415,7 @@ MidiPlaylist::contained_automation()
 
 
 bool
-MidiPlaylist::region_changed (PBD::PropertyChange what_changed, boost::shared_ptr<Region> region)
+MidiPlaylist::region_changed (const PBD::PropertyChange& what_changed, boost::shared_ptr<Region> region)
 {
 	if (in_flush || in_set_state) {
 		return false;
@@ -423,18 +423,13 @@ MidiPlaylist::region_changed (PBD::PropertyChange what_changed, boost::shared_pt
 
 	// Feeling rather uninterested today, but thanks for the heads up anyway!
 
-	PBD::PropertyChange our_interests = PBD::PropertyChange (/*MidiRegion::FadeInChanged|
-	                               MidiRegion::FadeOutChanged|
-	                               MidiRegion::FadeInActiveChanged|
-	                               MidiRegion::FadeOutActiveChanged|
-	                               MidiRegion::EnvelopeActiveChanged|
-	                               MidiRegion::ScaleAmplitudeChanged|
-	                               MidiRegion::EnvelopeChanged*/);
+	PBD::PropertyChange our_interests;
+
 	bool parent_wants_notify;
 
 	parent_wants_notify = Playlist::region_changed (what_changed, region);
 
-	if ((parent_wants_notify || (what_changed & our_interests))) {
+	if (parent_wants_notify || what_changed.contains (our_interests)) {
 		notify_contents_changed ();
 	}
 
diff --git a/libs/ardour/midi_region.cc b/libs/ardour/midi_region.cc
index f166dafda8..936ce047ee 100644
--- a/libs/ardour/midi_region.cc
+++ b/libs/ardour/midi_region.cc
@@ -47,23 +47,15 @@ using namespace std;
 using namespace ARDOUR;
 using namespace PBD;
 
-/** Basic MidiRegion constructor (one channel) */
-MidiRegion::MidiRegion (boost::shared_ptr<MidiSource> src)
-	: Region (src)
-{
-	assert(_name.val().find("/") == string::npos);
-	midi_source(0)->Switched.connect_same_thread (*this, boost::bind (&MidiRegion::switch_source, this, _1));
-}
-
 /* Basic MidiRegion constructor (many channels) */
 MidiRegion::MidiRegion (const SourceList& srcs)
 	: Region (srcs)
 {
-	assert(_name.val().find("/") == string::npos);
 	midi_source(0)->Switched.connect_same_thread (*this, boost::bind (&MidiRegion::switch_source, this, _1));
+	assert(_name.val().find("/") == string::npos);
+	assert(_type == DataType::MIDI);
 }
 
-
 /** Create a new MidiRegion, that is part of an existing one */
 MidiRegion::MidiRegion (boost::shared_ptr<const MidiRegion> other, frameoffset_t offset, bool offset_relative)
 	: Region (other, offset, offset_relative)
@@ -72,30 +64,6 @@ MidiRegion::MidiRegion (boost::shared_ptr<const MidiRegion> other, frameoffset_t
 	midi_source(0)->Switched.connect_same_thread (*this, boost::bind (&MidiRegion::switch_source, this, _1));
 }
 
-MidiRegion::MidiRegion (boost::shared_ptr<MidiSource> src, const XMLNode& node)
-	: Region (src, node)
-{
-	if (set_state (node, Stateful::loading_state_version)) {
-		throw failed_constructor();
-	}
-
-	midi_source(0)->Switched.connect_same_thread (*this, boost::bind (&MidiRegion::switch_source, this, _1));
-	assert(_name.val().find("/") == string::npos);
-	assert(_type == DataType::MIDI);
-}
-
-MidiRegion::MidiRegion (const SourceList& srcs, const XMLNode& node)
-	: Region (srcs, node)
-{
-	if (set_state (node, Stateful::loading_state_version)) {
-		throw failed_constructor();
-	}
-
-	midi_source(0)->Switched.connect_same_thread (*this, boost::bind (&MidiRegion::switch_source, this, _1));
-	assert(_name.val().find("/") == string::npos);
-	assert(_type == DataType::MIDI);
-}
-
 MidiRegion::~MidiRegion ()
 {
 }
diff --git a/libs/ardour/playlist.cc b/libs/ardour/playlist.cc
index 9d909d0fa6..f3a9c99497 100644
--- a/libs/ardour/playlist.cc
+++ b/libs/ardour/playlist.cc
@@ -666,7 +666,7 @@ Playlist::add_region_internal (boost::shared_ptr<Region> region, framepos_t posi
 		}
 	}
 
-	region->StateChanged.connect_same_thread (region_state_changed_connections, boost::bind (&Playlist::region_changed_proxy, this, _1, boost::weak_ptr<Region> (region)));
+	region->PropertyChanged.connect_same_thread (region_state_changed_connections, boost::bind (&Playlist::region_changed_proxy, this, _1, boost::weak_ptr<Region> (region)));
 
 	return true;
 }
@@ -1383,13 +1383,13 @@ Playlist::core_splice (framepos_t at, framecnt_t distance, boost::shared_ptr<Reg
 }
 
 void
-Playlist::region_bounds_changed (PropertyChange what_changed, boost::shared_ptr<Region> region)
+Playlist::region_bounds_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
 {
 	if (in_set_state || _splicing || _nudging || _shuffling) {
 		return;
 	}
 
-	if (what_changed & ARDOUR::PositionChanged) {
+	if (what_changed.contains (Properties::position)) {
 
 		/* remove it from the list then add it back in
 		   the right place again.
@@ -1410,15 +1410,15 @@ Playlist::region_bounds_changed (PropertyChange what_changed, boost::shared_ptr<
 		regions.insert (upper_bound (regions.begin(), regions.end(), region, cmp), region);
 	}
 
-	if (what_changed & PropertyChange (ARDOUR::PositionChanged|ARDOUR::LengthChanged)) {
+	if (what_changed.contains (Properties::position) || what_changed.contains (Properties::length)) {
 
 		frameoffset_t delta = 0;
 
-		if (what_changed & ARDOUR::PositionChanged) {
+		if (what_changed.contains (Properties::position)) {
 			delta = region->position() - region->last_position();
 		}
 
-		if (what_changed & ARDOUR::LengthChanged) {
+		if (what_changed.contains (Properties::length)) {
 			delta += region->length() - region->last_length();
 		}
 
@@ -1442,7 +1442,7 @@ Playlist::region_bounds_changed (PropertyChange what_changed, boost::shared_ptr<
 }
 
 void
-Playlist::region_changed_proxy (PropertyChange what_changed, boost::weak_ptr<Region> weak_region)
+Playlist::region_changed_proxy (const PropertyChange& what_changed, boost::weak_ptr<Region> weak_region)
 {
 	boost::shared_ptr<Region> region (weak_region.lock());
 
@@ -1456,26 +1456,38 @@ Playlist::region_changed_proxy (PropertyChange what_changed, boost::weak_ptr<Reg
 }
 
 bool
-Playlist::region_changed (PropertyChange what_changed, boost::shared_ptr<Region> region)
+Playlist::region_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
 {
-	PropertyChange our_interests = PropertyChange (Region::MuteChanged|Region::LayerChanged|Region::OpacityChanged);
+	PropertyChange our_interests;
+	PropertyChange bounds;
+	PropertyChange pos_and_length;
 	bool save = false;
 
 	if (in_set_state || in_flush) {
 		return false;
 	}
 
-	if (what_changed & BoundsChanged) {
+	our_interests.add (Properties::muted);
+	our_interests.add (Properties::layer);
+	our_interests.add (Properties::opaque);
+
+	bounds.add (Properties::start);
+	bounds.add (Properties::position);
+	bounds.add (Properties::length);
+
+	pos_and_length.add (Properties::position);
+	pos_and_length.add (Properties::length);
+
+	if (what_changed.contains (bounds)) {
 		region_bounds_changed (what_changed, region);
 		save = !(_splicing || _nudging);
 	}
 
-	if ((what_changed & our_interests) &&
-	    !(what_changed & PropertyChange (ARDOUR::PositionChanged|ARDOUR::LengthChanged))) {
+	if (what_changed.contains (our_interests) && !what_changed.contains (pos_and_length)) {
 		check_dependents (region, false);
 	}
 
-	if (what_changed & PropertyChange (ARDOUR::PositionChanged)) {
+	if (what_changed.contains (Properties::position)) {
 		notify_region_moved (region);
 	}
 
@@ -1484,7 +1496,7 @@ Playlist::region_changed (PropertyChange what_changed, boost::shared_ptr<Region>
 	   them, and we notify in ::relayer()
 	*/
 
-	if (what_changed & our_interests) {
+	if (what_changed.contains (our_interests)) {
 		save = true;
 	}
 
@@ -1973,7 +1985,7 @@ Playlist::set_state (const XMLNode& node, int version)
 				error << _("region state node has no ID, ignored") << endmsg;
 				continue;
 			}
-
+			
 			ID id = prop->value ();
 
 			if ((region = region_by_id (id))) {
diff --git a/libs/ardour/region.cc b/libs/ardour/region.cc
index 740a4abd5e..9cd8d49411 100644
--- a/libs/ardour/region.cc
+++ b/libs/ardour/region.cc
@@ -46,14 +46,6 @@ using namespace std;
 using namespace ARDOUR;
 using namespace PBD;
 
-PropertyChange Region::FadeChanged       = PBD::new_change ();
-PropertyChange Region::SyncOffsetChanged = PBD::new_change ();
-PropertyChange Region::MuteChanged       = PBD::new_change ();
-PropertyChange Region::OpacityChanged    = PBD::new_change ();
-PropertyChange Region::LockChanged       = PBD::new_change ();
-PropertyChange Region::LayerChanged      = PBD::new_change ();
-PropertyChange Region::HiddenChanged     = PBD::new_change ();
-
 namespace ARDOUR { 
 	namespace Properties {
 		PBD::PropertyDescriptor<bool> muted;
@@ -80,7 +72,7 @@ namespace ARDOUR {
 	}
 }
 	
-PBD::Signal1<void,boost::shared_ptr<ARDOUR::Region> > Region::RegionPropertyChanged;
+PBD::Signal2<void,boost::shared_ptr<ARDOUR::Region>,const PropertyChange&> Region::RegionPropertyChanged;
 
 void
 Region::make_property_quarks ()
@@ -137,27 +129,27 @@ Region::register_properties ()
 }
 
 #define REGION_DEFAULT_STATE(s,l) \
-	_muted (Properties::muted, MuteChanged, false)	     \
-	, _opaque (Properties::opaque, OpacityChanged, true) \
-	, _locked (Properties::locked, LockChanged, false) \
-	, _automatic (Properties::automatic, PropertyChange (0), false) \
-	, _whole_file (Properties::whole_file, PropertyChange (0), false) \
-	, _import (Properties::import, PropertyChange (0), false) \
-	, _external (Properties::external, PropertyChange (0), false) \
-	, _sync_marked (Properties::sync_marked, SyncOffsetChanged, false) \
-	, _left_of_split (Properties::left_of_split, PropertyChange (0), false) \
-	, _right_of_split (Properties::right_of_split, PropertyChange (0), false) \
-	, _hidden (Properties::hidden, HiddenChanged, false) \
-	, _position_locked (Properties::position_locked, PropertyChange (0), false) \
-	, _start (Properties::start, StartChanged, (s))	\
-	, _length (Properties::length, LengthChanged, (l))	\
-	, _position (Properties::position, PositionChanged, 0) \
-	, _sync_position (Properties::sync_position, SyncOffsetChanged, (s)) \
-	, _layer (Properties::layer, LayerChanged, 0)	\
-	, _ancestral_start (Properties::ancestral_start, PropertyChange (0), (s)) \
-	, _ancestral_length (Properties::ancestral_length, PropertyChange (0), (l)) \
-	, _stretch (Properties::stretch, PropertyChange (0), 1.0) \
-	, _shift (Properties::shift, PropertyChange (0), 1.0)
+	_muted (Properties::muted, false)	     \
+	, _opaque (Properties::opaque, true) \
+	, _locked (Properties::locked, false) \
+	, _automatic (Properties::automatic, false) \
+	, _whole_file (Properties::whole_file, false) \
+	, _import (Properties::import, false) \
+	, _external (Properties::external, false) \
+	, _sync_marked (Properties::sync_marked, false) \
+	, _left_of_split (Properties::left_of_split, false) \
+	, _right_of_split (Properties::right_of_split, false) \
+	, _hidden (Properties::hidden, false) \
+	, _position_locked (Properties::position_locked, false) \
+	, _start (Properties::start, (s))	\
+	, _length (Properties::length, (l))	\
+	, _position (Properties::position, 0) \
+	, _sync_position (Properties::sync_position, (s)) \
+	, _layer (Properties::layer, 0)	\
+	, _ancestral_start (Properties::ancestral_start, (s)) \
+	, _ancestral_length (Properties::ancestral_length, (l)) \
+	, _stretch (Properties::stretch, 1.0) \
+	, _shift (Properties::shift, 1.0)
 
 #define REGION_COPY_STATE(other) \
 	  _muted (other->_muted) \
@@ -194,7 +186,6 @@ Region::Region (Session& s, framepos_t start, framecnt_t length, const string& n
 	, _first_edit (EditChangesNothing)
 	, _frozen(0)
 	, _read_data_count(0)
-	, _pending_changed(PropertyChange (0))
 	, _last_layer_op(0)
 	, _pending_explicit_relayer (false)
 {
@@ -203,34 +194,6 @@ Region::Region (Session& s, framepos_t start, framecnt_t length, const string& n
 	/* no sources at this point */
 }
 
-/** Basic Region constructor (single source) */
-Region::Region (boost::shared_ptr<Source> src)
-	: SessionObject(src->session(), "toBeRenamed")
-	, _type (src->type())
-	, _no_property_changes (true)
-	, REGION_DEFAULT_STATE(0,0)
-	, _last_length (0)
-	, _last_position (0)
-        , _positional_lock_style (_type == DataType::AUDIO ? AudioTime : MusicTime)
-	, _first_edit (EditChangesNothing)
-	, _frozen(0)
-	, _valid_transients(false)
-	, _read_data_count(0)
-	, _pending_changed(PropertyChange (0))
-	, _last_layer_op(0)
-	, _pending_explicit_relayer (false)
-{
-	register_properties ();
-
-	_sources.push_back (src);
-	_master_sources.push_back (src);
-
-	src->DropReferences.connect_same_thread (*this, boost::bind (&Region::source_deleted, this, boost::weak_ptr<Source>(src)));
-	
-	assert (_sources.size() > 0);
-	assert (_type == src->type());
-}
-
 /** Basic Region constructor (many sources) */
 Region::Region (const SourceList& srcs)
 	: SessionObject(srcs.front()->session(), "toBeRenamed")
@@ -244,7 +207,6 @@ Region::Region (const SourceList& srcs)
 	, _frozen (0)
 	, _valid_transients(false)
 	, _read_data_count(0)
-	, _pending_changed(PropertyChange (0))
 	, _last_layer_op (0)
 	, _pending_explicit_relayer (false)
 {
@@ -277,7 +239,6 @@ Region::Region (boost::shared_ptr<const Region> other, frameoffset_t offset, boo
 	, _frozen (0)
 	, _valid_transients(false)
 	, _read_data_count(0)
-	, _pending_changed(PropertyChange (0))
 	, _last_layer_op (0)
 	, _pending_explicit_relayer (false)
 
@@ -387,7 +348,6 @@ Region::Region (boost::shared_ptr<const Region> other, const SourceList& srcs)
 	, _frozen (0)
 	, _valid_transients (false)
 	, _read_data_count (0)
-	, _pending_changed (PropertyChange(0))
 	, _last_layer_op (other->_last_layer_op)
 	, _pending_explicit_relayer (false)
 {
@@ -421,7 +381,6 @@ Region::Region (boost::shared_ptr<const Region> other)
 	, _frozen(0)
 	, _valid_transients(false)
 	, _read_data_count(0)
-	, _pending_changed(PropertyChange(0))
 	, _last_layer_op(other->_last_layer_op)
 	, _pending_explicit_relayer (false)
 {
@@ -442,74 +401,6 @@ Region::Region (boost::shared_ptr<const Region> other)
 	assert(_sources.size() > 0);
 }
 
-Region::Region (const SourceList& srcs, const XMLNode& node)
-	: SessionObject(srcs.front()->session(), X_("error: XML did not reset this"))
-	, _type (srcs.front()->type())
-	, REGION_DEFAULT_STATE(0,0)
-	, _last_length (0)
-	, _last_position (0)
-        , _positional_lock_style (_type == DataType::AUDIO ? AudioTime : MusicTime)
-	, _first_edit (EditChangesNothing)
-	, _frozen(0)
-	, _valid_transients(false)
-	, _read_data_count(0)
-	, _pending_changed(PropertyChange(0))
-	, _last_layer_op(0)
-	, _pending_explicit_relayer (false)
-{
-	const XMLProperty* prop;
-
-	register_properties ();
-
-	if ((prop = node.property (X_("id")))) {
-		_id = prop->value();
-	}
-
-	use_sources (srcs);
-
-	if (set_state (node, Stateful::loading_state_version)) {
-		throw failed_constructor();
-	}
-
-	assert(_type != DataType::NIL);
-	assert(_sources.size() > 0);
-	assert (_type == srcs.front()->type());
-
-}
-
-Region::Region (boost::shared_ptr<Source> src, const XMLNode& node)
-	: SessionObject(src->session(), X_("error: XML did not reset this"))
-	, _type (src->type())
-	, REGION_DEFAULT_STATE(0,0)
-	, _last_length (0)
-	, _last_position (0)
-        , _positional_lock_style (_type == DataType::AUDIO ? AudioTime : MusicTime)
-	, _first_edit (EditChangesNothing)
-	, _frozen (0)
-	, _read_data_count (0)
-	, _pending_changed (PropertyChange(0))
-	, _last_layer_op (0)
-	, _pending_explicit_relayer (false)
-{
-	const XMLProperty *prop;
-
-	register_properties ();
-
-	_sources.push_back (src);
-
-	if ((prop = node.property (X_("id")))) {
-		_id = prop->value();
-	}
-
-	if (set_state (node, Stateful::loading_state_version)) {
-		throw failed_constructor();
-	}
-
-	assert (_type != DataType::NIL);
-	assert (_sources.size() > 0);
-	assert (_type == src->type());
-}
-
 Region::~Region ()
 {
 	DEBUG_TRACE (DEBUG::Destruction, string_compose ("Region %1 destructor @ %2\n", _name, this));
@@ -527,7 +418,7 @@ Region::set_name (const std::string& str)
 	if (_name != str) {
 		SessionObject::set_name(str); // EMIT SIGNAL NameChanged()
 		assert(_name == str);
-		send_change (ARDOUR::NameChanged);
+		send_change (Properties::name);
 	}
 
 	return true;
@@ -567,7 +458,7 @@ Region::set_length (framecnt_t len, void */*src*/)
 			recompute_at_end ();
 		}
 
-		send_change (LengthChanged);
+		send_change (Properties::length);
 	}
 }
 
@@ -587,7 +478,7 @@ Region::first_edit ()
 		_name = _session.new_region_name (_name);
 		_first_edit = EditChangesNothing;
 
-		send_change (ARDOUR::NameChanged);
+		send_change (Properties::name);
 		RegionFactory::CheckNewRegion (shared_from_this());
 	}
 }
@@ -709,7 +600,7 @@ Region::set_position_internal (framepos_t pos, bool allow_bbt_recompute)
 	   a GUI that has moved its representation already.
 	*/
 
-	send_change (PositionChanged);
+	send_change (Properties::position);
 }
 
 void
@@ -734,7 +625,7 @@ Region::set_position_on_top (framepos_t pos, void* /*src*/)
 	   a GUI that has moved its representation already.
 	*/
 
-	send_change (PositionChanged);
+	send_change (Properties::position);
 }
 
 void
@@ -772,7 +663,7 @@ Region::nudge_position (frameoffset_t n, void* /*src*/)
 		}
 	}
 
-	send_change (PositionChanged);
+	send_change (Properties::position);
 }
 
 void
@@ -806,7 +697,7 @@ Region::set_start (framepos_t pos, void* /*src*/)
 		first_edit ();
 		invalidate_transients ();
 
-		send_change (StartChanged);
+		send_change (Properties::start);
 	}
 }
 
@@ -856,7 +747,7 @@ Region::trim_start (framepos_t new_position, void */*src*/)
 	_whole_file = false;
 	first_edit ();
 
-	send_change (StartChanged);
+	send_change (Properties::start);
 }
 
 void
@@ -971,34 +862,39 @@ Region::trim_to_internal (framepos_t position, framecnt_t length, void */*src*/)
 		return;
 	}
 
-	PropertyChange what_changed = PropertyChange (0);
+	PropertyChange what_changed;
 
 	if (_start != new_start) {
 		_start = new_start;
-		what_changed = PropertyChange (what_changed|StartChanged);
+		what_changed.add (Properties::start);
 	}
 	if (_length != length) {
 		if (!_frozen) {
 			_last_length = _length;
 		}
 		_length = length;
-		what_changed = PropertyChange (what_changed|LengthChanged);
+		what_changed.add (Properties::length);
 	}
 	if (_position != position) {
 		if (!_frozen) {
 			_last_position = _position;
 		}
 		_position = position;
-		what_changed = PropertyChange (what_changed|PositionChanged);
+		what_changed.add (Properties::position);
 	}
 
 	_whole_file = false;
 
-	if (what_changed & (StartChanged|LengthChanged)) {
+	PropertyChange start_and_length;
+
+	start_and_length.add (Properties::start);
+	start_and_length.add (Properties::length);
+
+	if (what_changed.contains (start_and_length)) {
 		first_edit ();
 	}
 
-	if (what_changed) {
+	if (!what_changed.empty()) {
 		send_change (what_changed);
 	}
 }
@@ -1008,7 +904,7 @@ Region::set_hidden (bool yn)
 {
 	if (hidden() != yn) {
 		_hidden = yn;
-		send_change (HiddenChanged);
+		send_change (Properties::hidden);
 	}
 }
 
@@ -1031,7 +927,7 @@ Region::set_muted (bool yn)
 {
 	if (muted() != yn) {
 		_muted = yn;
-		send_change (MuteChanged);
+		send_change (Properties::muted);
 	}
 }
 
@@ -1040,7 +936,7 @@ Region::set_opaque (bool yn)
 {
 	if (opaque() != yn) {
 		_opaque = yn;
-		send_change (OpacityChanged);
+		send_change (Properties::opaque);
 	}
 }
 
@@ -1049,7 +945,7 @@ Region::set_locked (bool yn)
 {
 	if (locked() != yn) {
 		_locked = yn;
-		send_change (LockChanged);
+		send_change (Properties::locked);
 	}
 }
 
@@ -1058,7 +954,7 @@ Region::set_position_locked (bool yn)
 {
 	if (position_locked() != yn) {
 		_position_locked = yn;
-		send_change (LockChanged);
+		send_change (Properties::locked);
 	}
 }
 
@@ -1073,7 +969,7 @@ Region::set_sync_position (framepos_t absolute_pos)
 		if (!_frozen) {
 			maybe_uncopy ();
 		}
-		send_change (SyncOffsetChanged);
+		send_change (Properties::sync_position);
 	}
 }
 
@@ -1085,7 +981,7 @@ Region::clear_sync_position ()
 		if (!_frozen) {
 			maybe_uncopy ();
 		}
-		send_change (SyncOffsetChanged);
+		send_change (Properties::sync_position);
 	}
 }
 
@@ -1184,7 +1080,7 @@ Region::set_layer (layer_t l)
 	if (_layer != l) {
 		_layer = l;
 
-		send_change (LayerChanged);
+		send_change (Properties::layer);
 	}
 }
 
@@ -1239,7 +1135,7 @@ Region::get_state ()
 int
 Region::set_state (const XMLNode& node, int version)
 {
-	PropertyChange what_changed = PropertyChange (0);
+	PropertyChange what_changed;
 	return _set_state (node, version, what_changed, true);
 }
 
@@ -1248,6 +1144,8 @@ Region::_set_state (const XMLNode& node, int version, PropertyChange& what_chang
 {
 	const XMLProperty* prop;
 
+	cerr << "about to call ::set_properties for an XMLNode\n";
+
 	what_changed = set_properties (node);
 
 	if ((prop = node.property (X_("id")))) {
@@ -1300,7 +1198,11 @@ Region::_set_state (const XMLNode& node, int version, PropertyChange& what_chang
 	}
 
 	if (send) {
-		cerr << _name << ": final change to be sent: " << hex << what_changed << dec << endl;
+		cerr << _name << ": final change to be sent: ";
+		for (PropertyChange::iterator i = what_changed.begin(); i != what_changed.end(); ++i) {
+			cerr << g_quark_to_string ((GQuark) *i) << ' ';
+		}
+		cerr << endl;
 		send_change (what_changed);
 	}
 
@@ -1318,7 +1220,7 @@ Region::freeze ()
 void
 Region::thaw ()
 {
-	PropertyChange what_changed = PropertyChange (0);
+	PropertyChange what_changed;
 
 	{
 		Glib::Mutex::Lock lm (_lock);
@@ -1327,18 +1229,18 @@ Region::thaw ()
 			return;
 		}
 
-		if (_pending_changed) {
+		if (!_pending_changed.empty()) {
 			what_changed = _pending_changed;
-			_pending_changed = PropertyChange (0);
+			_pending_changed.clear ();
 		}
 	}
 
-	if (what_changed == PropertyChange (0)) {
+	if (what_changed.empty()) {
 		return;
 	}
 
-	if (what_changed & LengthChanged) {
-		if (what_changed & PositionChanged) {
+	if (what_changed.contains (Properties::length)) {
+		if (what_changed.contains (Properties::position)) {
 			recompute_at_start ();
 		}
 		recompute_at_end ();
@@ -1348,20 +1250,21 @@ Region::thaw ()
 }
 
 void
-Region::send_change (PropertyChange what_changed)
+Region::send_change (const PropertyChange& what_changed)
 {
+	if (what_changed.empty()) {
+		return;
+	}
 
 	{
 		Glib::Mutex::Lock lm (_lock);
 		if (_frozen) {
-			_pending_changed = PropertyChange (_pending_changed|what_changed);
+			_pending_changed.add (what_changed);
 			return;
 		}
 	}
 
-	cerr << _name << " actually sends " << hex << what_changed << dec << " @" << get_microseconds() << endl;
-	StateChanged (what_changed);
-	cerr << _name << " done with " << hex << what_changed << dec << " @" << get_microseconds() << endl;
+	PropertyChanged (what_changed);
 
 	if (!_no_property_changes) {
 		
@@ -1371,9 +1274,7 @@ Region::send_change (PropertyChange what_changed)
 
 		try {
 			boost::shared_ptr<Region> rptr = shared_from_this();
-			cerr << _name << " actually sends prop change " << hex << what_changed << dec <<  " @ " << get_microseconds() << endl;
-			RegionPropertyChanged (rptr);
-			cerr << _name << " done with prop change  @ " << get_microseconds() << endl;
+			RegionPropertyChanged (rptr, what_changed);
 
 		} catch (...) {
 			/* no shared_ptr available, relax; */
@@ -1612,11 +1513,9 @@ Region::use_sources (SourceList const & s)
 }
 
 
-PropertyChange
+bool
 Region::set_property (const PropertyBase& prop)
 {
-	PropertyChange c = PropertyChange (0);
-
 	DEBUG_TRACE (DEBUG::Properties,  string_compose ("region %1 set property %2\n", _name.val(), prop.property_name()));
 
 	if (prop == Properties::muted.id) {
@@ -1625,7 +1524,7 @@ Region::set_property (const PropertyBase& prop)
 			DEBUG_TRACE (DEBUG::Properties, string_compose ("region %1 muted changed from %2 to %3",
 									_name.val(), _muted.val(), val));
 			_muted = val;
-			c = MuteChanged;
+			return true;
 		}
 	} else if (prop == Properties::opaque.id) {
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
@@ -1633,7 +1532,7 @@ Region::set_property (const PropertyBase& prop)
 			DEBUG_TRACE (DEBUG::Properties, string_compose ("region %1 opaque changed from %2 to %3",
 									_name.val(), _opaque.val(), val));
 			_opaque = val;
-			c = OpacityChanged;
+			return true;
 		}
 	} else if (prop == Properties::locked.id) {
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
@@ -1641,7 +1540,7 @@ Region::set_property (const PropertyBase& prop)
 			DEBUG_TRACE (DEBUG::Properties, string_compose ("region %1 locked changed from %2 to %3",
 									_name.val(), _locked.val(), val));
 			_locked = val;
-			c = LockChanged;
+			return true;
 		}
 	} else if (prop == Properties::automatic.id) {
 		_automatic = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
@@ -1661,51 +1560,35 @@ Region::set_property (const PropertyBase& prop)
 		bool val = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
 		if (val != _hidden) {
 			_hidden = val;
-			c = HiddenChanged;
+			return true;
 		}
 	} else if (prop == Properties::position_locked.id) {
 		_position_locked = dynamic_cast<const PropertyTemplate<bool>*>(&prop)->val();
 	} else if (prop == Properties::start.id) {
 		_start = dynamic_cast<const PropertyTemplate<framepos_t>*>(&prop)->val();
 	} else if (prop == Properties::length.id) {
-		const PropertyTemplate<framecnt_t>* pt1 = dynamic_cast<const PropertyTemplate<framecnt_t>* >(&prop);
-		const PropertyTemplate<int>* pt2 = dynamic_cast<const PropertyTemplate<int>* >(&prop);
-		
-		cerr << "Cast to frmecnt = " << pt1 << " to int = " << pt2 << endl;
-
 		framecnt_t val = dynamic_cast<const PropertyTemplate<framecnt_t>* > (&prop)->val();
 		if (val != _length) {
-			DEBUG_TRACE (DEBUG::Properties, string_compose ("region %1 length changed from %2 to %3",
-									_name.val(), _length.val(), val));
 			_length = val;
-			c = LengthChanged;
-		} else {
-			DEBUG_TRACE (DEBUG::Properties, string_compose ("length %1 matches %2\n", _length.val(), val));
+			return true;
 		}
-
 	} else if (prop == Properties::position.id) {
 		framepos_t val = dynamic_cast<const PropertyTemplate<framepos_t>*>(&prop)->val();
 		if (val != _position) {
-			DEBUG_TRACE (DEBUG::Properties, string_compose ("region %1 position changed from %2 to %3",
-									_name.val(), _position.val(), val));
 			_position = val;
-			c = PositionChanged;
+			return true;
 		}
 	} else if (prop == Properties::sync_position.id) {
 		framepos_t val = dynamic_cast<const PropertyTemplate<framepos_t>*>(&prop)->val();
 		if (val != _sync_position) {
-			DEBUG_TRACE (DEBUG::Properties, string_compose ("region %1 syncpos changed from %2 to %3",
-									_name.val(), _sync_position, val));
 			_sync_position = val;
-			c = SyncOffsetChanged;
+			return true;
 		}
 	} else if (prop == Properties::layer.id) {
 		layer_t val = dynamic_cast<const PropertyTemplate<layer_t>*>(&prop)->val();
 		if (val != _layer) {
-			DEBUG_TRACE (DEBUG::Properties, string_compose ("region %1 syncpos changed from %2 to %3",
-									_name.val(), _sync_position, val));
 			_layer = val;
-			c = LayerChanged;
+			return true;
 		}
 	} else if (prop == Properties::ancestral_start.id) {
 		_ancestral_start = dynamic_cast<const PropertyTemplate<framepos_t>*>(&prop)->val();
@@ -1719,5 +1602,5 @@ Region::set_property (const PropertyBase& prop)
 		return SessionObject::set_property (prop);
 	}
 	
-	return c;
+	return false;
 }
diff --git a/libs/ardour/region_factory.cc b/libs/ardour/region_factory.cc
index ae4df173e4..42a5629e4a 100644
--- a/libs/ardour/region_factory.cc
+++ b/libs/ardour/region_factory.cc
@@ -209,38 +209,9 @@ RegionFactory::create (boost::shared_ptr<Region> region, const SourceList& srcs,
 boost::shared_ptr<Region>
 RegionFactory::create (boost::shared_ptr<Source> src, const PropertyList& plist, bool announce)
 {
-	boost::shared_ptr<Region> ret; 
-	boost::shared_ptr<AudioSource> as;
-	boost::shared_ptr<MidiSource> ms;
-
-	if ((as = boost::dynamic_pointer_cast<AudioSource>(src)) != 0) {
-
-		AudioRegion* ar = new AudioRegion (as);
-		boost_debug_shared_ptr_mark_interesting (ar, "Region");
-
-		boost::shared_ptr<AudioRegion> arp (ar);
-		ret = boost::static_pointer_cast<Region> (arp);
-
-	} else if ((ms = boost::dynamic_pointer_cast<MidiSource>(src)) != 0) {
-		MidiRegion* mr = new MidiRegion (ms);
-		boost_debug_shared_ptr_mark_interesting (mr, "Region");
-
-		boost::shared_ptr<MidiRegion> mrp (mr);
-		ret = boost::static_pointer_cast<Region> (mrp);
-	}
-
-	if (ret) {
-		ret->set_properties (plist);
-		ret->unlock_property_changes ();
-
-		map_add (ret);
-
-		if (announce) {
-			CheckNewRegion (ret);
-		}
-	}
-
-	return ret;
+	SourceList srcs;
+	srcs.push_back (src);
+	return create (srcs, plist, announce);
 }
 
 boost::shared_ptr<Region>
@@ -283,18 +254,9 @@ RegionFactory::create (const SourceList& srcs, const PropertyList& plist, bool a
 boost::shared_ptr<Region>
 RegionFactory::create (Session& session, XMLNode& node, bool yn)
 {
-	boost::shared_ptr<Region> r = session.XMLRegionFactory (node, yn);
-
-	if (r) {
-		r->unlock_property_changes ();
-		map_add (r);
-		CheckNewRegion (r);
-	}
-
-	return r;
+	return session.XMLRegionFactory (node, yn);
 }
 
-
 boost::shared_ptr<Region>
 RegionFactory::create (SourceList& srcs, const XMLNode& node)
 {
@@ -306,7 +268,7 @@ RegionFactory::create (SourceList& srcs, const XMLNode& node)
 
 	if (srcs[0]->type() == DataType::AUDIO) {
 
-		AudioRegion* ar = new AudioRegion (srcs, node);
+		AudioRegion* ar = new AudioRegion (srcs);
 		boost_debug_shared_ptr_mark_interesting (ar, "Region");
 
 		boost::shared_ptr<AudioRegion> arp (ar);
@@ -314,16 +276,21 @@ RegionFactory::create (SourceList& srcs, const XMLNode& node)
 
 	} else if (srcs[0]->type() == DataType::MIDI) {
 		
-		MidiRegion* mr = new MidiRegion (srcs, node);
+		MidiRegion* mr = new MidiRegion (srcs);
 
 		boost::shared_ptr<MidiRegion> mrp (mr);
 		ret = boost::static_pointer_cast<Region> (mrp);
 	}
 
 	if (ret) {
-		ret->unlock_property_changes ();
-		map_add (ret);
-		CheckNewRegion (ret);
+
+		if (ret->set_state (node, Stateful::loading_state_version)) {
+			ret.reset ();
+		} else {
+			ret->unlock_property_changes ();
+			map_add (ret);
+			CheckNewRegion (ret);
+		}
 	}
 
 	return ret;
diff --git a/libs/ardour/route_group.cc b/libs/ardour/route_group.cc
index 5b998d22f7..5e50c15457 100644
--- a/libs/ardour/route_group.cc
+++ b/libs/ardour/route_group.cc
@@ -40,9 +40,6 @@ using namespace ARDOUR;
 using namespace PBD;
 using namespace std;
 
-PropertyChange RouteGroup::FlagsChange = new_change ();
-PropertyChange RouteGroup::PropertiesChange = new_change ();
-
 namespace ARDOUR {
 	namespace Properties {
 		PropertyDescriptor<bool> relative;
@@ -70,15 +67,15 @@ RouteGroup::make_property_quarks ()
 	Properties::edit.id = g_quark_from_static_string (X_("edit"));
 }
 
-#define ROUTE_GROUP_DEFAULT_PROPERTIES  _relative (Properties::relative, FlagsChange, false) \
-	, _active (Properties::active, FlagsChange, false) \
-	, _hidden (Properties::hidden, FlagsChange, false) \
-	, _gain (Properties::gain, PropertiesChange, false) \
-	, _mute (Properties::mute, PropertiesChange, false) \
-	, _solo (Properties::solo, PropertiesChange , false) \
-	, _recenable (Properties::recenable, PropertiesChange, false) \
-	, _select (Properties::select, PropertiesChange, false) \
-	, _edit (Properties::edit, PropertiesChange , false)
+#define ROUTE_GROUP_DEFAULT_PROPERTIES  _relative (Properties::relative, false) \
+	, _active (Properties::active, false) \
+	, _hidden (Properties::hidden, false) \
+	, _gain (Properties::gain, false) \
+	, _mute (Properties::mute, false) \
+	, _solo (Properties::solo, false) \
+	, _recenable (Properties::recenable, false) \
+	, _select (Properties::select, false) \
+	, _edit (Properties::edit, false)
 
 RouteGroup::RouteGroup (Session& s, const string &n)
 	: SessionObject (s, n)
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index e5b57115c1..decb2603fe 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -2810,7 +2810,7 @@ Session::add_regions (vector<boost::shared_ptr<Region> >& new_regions)
 				}
 			}
 
-			region->StateChanged.connect_same_thread (*this, boost::bind (&Session::region_changed, this, _1, boost::weak_ptr<Region>(region)));
+			region->PropertyChanged.connect_same_thread (*this, boost::bind (&Session::region_changed, this, _1, boost::weak_ptr<Region>(region)));
 			update_region_name_map (region);
 		}
 
@@ -2840,7 +2840,7 @@ Session::update_region_name_map (boost::shared_ptr<Region> region)
 }
 
 void
-Session::region_changed (PropertyChange what_changed, boost::weak_ptr<Region> weak_region)
+Session::region_changed (const PropertyChange& what_changed, boost::weak_ptr<Region> weak_region)
 {
 	boost::shared_ptr<Region> region (weak_region.lock ());
 
@@ -2848,12 +2848,12 @@ Session::region_changed (PropertyChange what_changed, boost::weak_ptr<Region> we
 		return;
 	}
 
-	if (what_changed & Region::HiddenChanged) {
+	if (what_changed.contains (Properties::hidden)) {
 		/* relay hidden changes */
 		RegionHiddenChange (region);
 	}
 
-	if (what_changed & NameChanged) {
+	if (what_changed.contains (Properties::name)) {
 		update_region_name_map (region);
 	}
 }
@@ -3675,7 +3675,7 @@ Session::bundle_by_name (string name) const
 }
 
 void
-Session::tempo_map_changed (PropertyChange)
+Session::tempo_map_changed (const PropertyChange&)
 {
 	clear_clicks ();
 
diff --git a/libs/ardour/session_object.cc b/libs/ardour/session_object.cc
index 0dcda09f26..b245b43ae5 100644
--- a/libs/ardour/session_object.cc
+++ b/libs/ardour/session_object.cc
@@ -37,27 +37,19 @@ SessionObject::make_property_quarks ()
 	Properties::name.id = g_quark_from_static_string (X_("name"));
 }
 
-PropertyChange 
+bool
 SessionObject::set_property (const PropertyBase& prop)
 {
-	PropertyChange c = PropertyChange (0);
-
-	DEBUG_TRACE (DEBUG::Properties,  string_compose ("session object %1 set property %2\n", _name.val(), prop.property_name()));
-	
 	if (prop == Properties::name.id) {
 		std::string str = dynamic_cast<const PropertyTemplate<std::string>*>(&prop)->val();
-		cerr << "prop @ " << &prop << " has quark " << prop.id() << " str value = " << str << endl;
-		cerr << "nameprop @ " << &_name << " has quark " << _name.id() << " str value = " << _name.val() << endl;
 		if (_name != str) {
 			DEBUG_TRACE (DEBUG::Properties, string_compose ("session object named %1 renamed %2\n",
 									_name.val(), str));
 			_name = str;
-			c = _name.change();
-		} else {
-			DEBUG_TRACE (DEBUG::Properties, string_compose ("name %1 matches %2\n", _name.val(), str));
-		}
+			return true;
+		} 
 	}
-	
-	return c;
+
+	return false;
 }
 
diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index face9388bc..434410b39e 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -165,7 +165,7 @@ Session::first_stage_init (string fullpath, string snapshot_name)
 	_base_frame_rate = _current_frame_rate;
 
 	_tempo_map = new TempoMap (_current_frame_rate);
-	_tempo_map->StateChanged.connect_same_thread (*this, boost::bind (&Session::tempo_map_changed, this, _1));
+	_tempo_map->PropertyChanged.connect_same_thread (*this, boost::bind (&Session::tempo_map_changed, this, _1));
 
 
 	_non_soloed_outs_muted = false;
diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index be34b79ccc..93470e369b 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -299,7 +299,7 @@ void
 TempoMap::move_tempo (TempoSection& tempo, const BBT_Time& when)
 {
 	if (move_metric_section (tempo, when) == 0) {
-		StateChanged (PropertyChange (0));
+		PropertyChanged (PropertyChange ());
 	}
 }
 
@@ -307,7 +307,7 @@ void
 TempoMap::move_meter (MeterSection& meter, const BBT_Time& when)
 {
 	if (move_metric_section (meter, when) == 0) {
-		StateChanged (PropertyChange (0));
+		PropertyChanged (PropertyChange ());
 	}
 }
 
@@ -334,7 +334,7 @@ TempoMap::remove_tempo (const TempoSection& tempo)
 	}
 
 	if (removed) {
-		StateChanged (PropertyChange (0));
+		PropertyChanged (PropertyChange ());
 	}
 }
 
@@ -361,7 +361,7 @@ TempoMap::remove_meter (const MeterSection& tempo)
 	}
 
 	if (removed) {
-		StateChanged (PropertyChange (0));
+		PropertyChanged (PropertyChange ());
 	}
 }
 
@@ -406,7 +406,7 @@ TempoMap::add_tempo (const Tempo& tempo, BBT_Time where)
 		do_insert (new TempoSection (where, tempo.beats_per_minute(), tempo.note_type()), true);
 	}
 
-	StateChanged (PropertyChange (0));
+	PropertyChanged (PropertyChange ());
 }
 
 void
@@ -417,7 +417,7 @@ TempoMap::add_tempo (const Tempo& tempo, nframes64_t where)
 		do_insert (new TempoSection (where, tempo.beats_per_minute(), tempo.note_type()), false);
 	}
 
-	StateChanged (PropertyChange (0));
+	PropertyChanged (PropertyChange ());
 }
 
 void
@@ -445,7 +445,7 @@ TempoMap::replace_tempo (TempoSection& existing, const Tempo& replacement)
 	}
 
 	if (replaced) {
-		StateChanged (PropertyChange (0));
+		PropertyChanged (PropertyChange ());
 	}
 }
 
@@ -474,7 +474,7 @@ TempoMap::add_meter (const Meter& meter, BBT_Time where)
 		do_insert (new MeterSection (where, meter.beats_per_bar(), meter.note_divisor()), true);
 	}
 
-	StateChanged (PropertyChange (0));
+	PropertyChanged (PropertyChange ());
 }
 
 void
@@ -485,7 +485,7 @@ TempoMap::add_meter (const Meter& meter, nframes64_t where)
 		do_insert (new MeterSection (where, meter.beats_per_bar(), meter.note_divisor()), false);
 	}
 
-	StateChanged (PropertyChange (0));
+	PropertyChanged (PropertyChange ());
 }
 
 void
@@ -511,7 +511,7 @@ TempoMap::replace_meter (MeterSection& existing, const Meter& replacement)
 	}
 
 	if (replaced) {
-		StateChanged (PropertyChange (0));
+		PropertyChanged (PropertyChange ());
 	}
 }
 
@@ -524,7 +524,7 @@ TempoMap::change_initial_tempo (double beats_per_minute, double note_type)
 	for (Metrics::iterator i = metrics->begin(); i != metrics->end(); ++i) {
 		if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
 			*((Tempo*) t) = newtempo;
-			StateChanged (PropertyChange (0));
+			PropertyChanged (PropertyChange ());
 			break;
 		}
 	}
@@ -570,7 +570,7 @@ TempoMap::change_existing_tempo_at (nframes64_t where, double beats_per_minute,
 	/* reset */
 
 	*((Tempo*)prev) = newtempo;
-	StateChanged (PropertyChange (0));
+	PropertyChanged (PropertyChange ());
 }
 
 const MeterSection&
@@ -1609,7 +1609,7 @@ TempoMap::set_state (const XMLNode& node, int /*version*/)
 		}
 	}
 
-	StateChanged (PropertyChange (0));
+	PropertyChanged (PropertyChange ());
 
 	return 0;
 }
@@ -1673,7 +1673,7 @@ TempoMap::insert_time (nframes64_t where, nframes64_t amount)
 
 	timestamp_metrics (false);
 
-	StateChanged (PropertyChange (0));
+	PropertyChanged (PropertyChange ());
 }
 
 BBT_Time