diff --git a/gtk2_ardour/editor_drag.cc b/gtk2_ardour/editor_drag.cc
index 0dedff5446..c7e96b27f7 100644
--- a/gtk2_ardour/editor_drag.cc
+++ b/gtk2_ardour/editor_drag.cc
@@ -3301,20 +3301,69 @@ TempoMarkerDrag::motion (GdkEvent* event, bool first_move)
 
 		/* use the new marker for the grab */
 		swap_grab (&_marker->the_item(), 0, GDK_CURRENT_TIME);
+		_marker->hide();
 
+		TempoMap& map (_editor->session()->tempo_map());
+		/* get current state */
+		before_state = &map.get_state();
 		if (!_copy) {
 			_editor->begin_reversible_command (_("move tempo mark"));
-			TempoMap& map (_editor->session()->tempo_map());
-			/* get current state */
-			before_state = &map.get_state();
+		} else {
+			_editor->begin_reversible_command (_("copy tempo mark"));
+			framepos_t frame;
+			bool use_snap = false;
+
+			if (!_editor->snap_musical()) {
+				frame = adjusted_current_frame (event);
+			} else {
+				frame = adjusted_current_frame (event, false);
+				if (ArdourKeyboard::indicates_snap (event->button.state)) {
+					if (_editor->snap_mode() == Editing::SnapOff) {
+						use_snap = true;
+					} else {
+						use_snap = false;
+					}
+				} else {
+					if (_editor->snap_mode() == Editing::SnapOff) {
+						use_snap = false;
+					} else {
+						use_snap = true;
+					}
+				}
+			}
+
+			Timecode::BBT_Time bbt;
+			map.bbt_time (frame, bbt);
+
+			/* add new tempo section to map, ensuring we don't refer to existing tempos for snap */
+
+			if (_real_section->position_lock_style() == MusicTime) {
+				if (use_snap && _editor->snap_type() == SnapToBar) {
+					map.round_bbt (bbt, -1);
+				} else if (use_snap) {
+					map.round_bbt (bbt, _editor->get_grid_beat_divisions (0));
+				}
+				double const pulse = map.predict_tempo_pulse (_real_section, map.frame_time (bbt));
+				_real_section = map.add_tempo (_marker->tempo(), pulse, _real_section->type());
+			} else {
+				if (use_snap && _editor->snap_type() == SnapToBar) {
+					map.round_bbt (bbt, -1);
+				} else if (use_snap) {
+					map.round_bbt (bbt, _editor->get_grid_beat_divisions (0));
+				}
+				if (use_snap) {
+					frame = map.predict_tempo_frame (_real_section, bbt);
+				}
+				_real_section = map.add_tempo (_marker->tempo(), frame, _real_section->type());
+			}
 		}
-		_marker->hide();
+
 	}
 
 	framepos_t pf;
 	Tempo const tp = _marker->tempo();
 
-	if (Keyboard::modifier_state_equals (event->button.state, ArdourKeyboard::constraint_modifier ())) {
+	if (ArdourKeyboard::indicates_snap (event->button.state)) {
 		double new_bpm = _real_section->beats_per_minute() + ((last_pointer_y() - current_pointer_y()) / 5.0);
 		_editor->session()->tempo_map().gui_change_tempo (_real_section, Tempo (new_bpm, _real_section->note_type()));
 		stringstream strs;
@@ -3322,8 +3371,14 @@ TempoMarkerDrag::motion (GdkEvent* event, bool first_move)
 		show_verbose_cursor_text (strs.str());
 	} else if (_movable) {
 		if (!_editor->snap_musical()) {
+			/* snap normally (this is not self-referential).*/
 			pf = adjusted_current_frame (event);
 		} else {
+			/* but this is.
+			   we can't use the map for anything related to tempo,
+			   so we round bbt using meters, which have no dependency
+			   on pulse for this kind of thing.
+			*/
 			bool use_snap;
 			TempoMap& map (_editor->session()->tempo_map());
 
@@ -3387,38 +3442,11 @@ TempoMarkerDrag::finished (GdkEvent* event, bool movement_occurred)
 		return;
 	}
 
-
 	TempoMap& map (_editor->session()->tempo_map());
 
-	if (_copy == true) {
-		_editor->begin_reversible_command (_("copy tempo mark"));
-		XMLNode &before = map.get_state();
-
-		if (_marker->tempo().position_lock_style() == MusicTime) {
-			double const pulse = map.predict_tempo_pulse (_real_section, _real_section->frame());
-			map.add_tempo (_marker->tempo(), pulse, _marker->tempo().type());
-		} else {
-			map.add_tempo (_marker->tempo(), _real_section->frame(), _marker->tempo().type());
-		}
-
-		XMLNode &after = map.get_state();
-		_editor->session()->add_command (new MementoCommand<TempoMap>(map, &before, &after));
-		_editor->commit_reversible_command ();
-
-	} else {
-		if (_marker->tempo().position_lock_style() == MusicTime) {
-			double const pulse = map.predict_tempo_pulse (_real_section, _real_section->frame());
-			map.replace_tempo (*_real_section, Tempo (_real_section->beats_per_minute(), _real_section->note_type())
-					   , pulse, _marker->tempo().type());
-		} else {
-			map.replace_tempo (*_real_section, Tempo (_real_section->beats_per_minute(), _real_section->note_type())
-					   , _real_section->frame(), _marker->tempo().type());
-		}
-
-		XMLNode &after = map.get_state();
-		_editor->session()->add_command (new MementoCommand<TempoMap>(map, before_state, &after));
-		_editor->commit_reversible_command ();
-	}
+	XMLNode &after = map.get_state();
+	_editor->session()->add_command (new MementoCommand<TempoMap>(map, before_state, &after));
+	_editor->commit_reversible_command ();
 
 	// delete the dummy marker we used for visual representation while moving.
 	// a new visual marker will show up automatically.
@@ -3431,12 +3459,7 @@ TempoMarkerDrag::aborted (bool moved)
 	_marker->set_position (_marker->tempo().frame());
 	if (moved) {
 		TempoMap& map (_editor->session()->tempo_map());
-		/* we removed it before, so add it back now */
-		if (_marker->tempo().position_lock_style() == MusicTime) {
-			map.add_tempo (_marker->tempo(), _marker->tempo().pulse(), _marker->tempo().type());
-		} else {
-			map.add_tempo (_marker->tempo(), _marker->tempo().frame(), _marker->tempo().type());
-		}
+		map.set_state (*before_state, Stateful::current_state_version);
 		// delete the dummy marker we used for visual representation while moving.
 		// a new visual marker will show up automatically.
 		delete _marker;
diff --git a/gtk2_ardour/editor_tempodisplay.cc b/gtk2_ardour/editor_tempodisplay.cc
index 3931e0bf09..fecdeb0ecb 100644
--- a/gtk2_ardour/editor_tempodisplay.cc
+++ b/gtk2_ardour/editor_tempodisplay.cc
@@ -368,7 +368,7 @@ Editor::edit_tempo_section (TempoSection* section)
 	double nt = tempo_dialog.get_note_type ();
 	Timecode::BBT_Time when;
 
-	tempo_dialog.get_bbt_time(when);
+	tempo_dialog.get_bbt_time (when);
 	double const beat = _session->tempo_map().bbt_to_beats (when);
 
 	bpm = max (0.01, bpm);
diff --git a/libs/ardour/ardour/tempo.h b/libs/ardour/ardour/tempo.h
index 98c6e82c16..1a37ecffe5 100644
--- a/libs/ardour/ardour/tempo.h
+++ b/libs/ardour/ardour/tempo.h
@@ -373,8 +373,8 @@ class LIBARDOUR_API TempoMap : public PBD::StatefulDestructible
 	const MeterSection& meter_section_at (framepos_t frame) const;
 	const MeterSection& meter_section_at (const double& beat) const;
 
-	void add_tempo (const Tempo&, const double& pulse, TempoSection::Type type);
-	void add_tempo (const Tempo&, const framepos_t& frame, TempoSection::Type type);
+	TempoSection* add_tempo (const Tempo&, const double& pulse, TempoSection::Type type);
+	TempoSection* add_tempo (const Tempo&, const framepos_t& frame, TempoSection::Type type);
 
 	MeterSection* add_meter (const Meter&, const double& beat, const Timecode::BBT_Time& where);
 	MeterSection* add_meter (const Meter&, const framepos_t& frame, const double& beat, const Timecode::BBT_Time& where);
@@ -489,8 +489,8 @@ private:
 
 	void do_insert (MetricSection* section);
 
-	void add_tempo_locked (const Tempo&, double pulse, bool recompute, TempoSection::Type type);
-	void add_tempo_locked (const Tempo&, framepos_t frame, bool recompute, TempoSection::Type type);
+	TempoSection* add_tempo_locked (const Tempo&, double pulse, bool recompute, TempoSection::Type type);
+	TempoSection* add_tempo_locked (const Tempo&, framepos_t frame, bool recompute, TempoSection::Type type);
 
 	MeterSection* add_meter_locked (const Meter&, double beat, Timecode::BBT_Time where, bool recompute);
 	MeterSection* add_meter_locked (const Meter&, framepos_t frame, double beat, Timecode::BBT_Time where, bool recompute);
diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index 88199a0d64..d4c0a1d639 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -198,7 +198,7 @@ double
 TempoSection::tempo_at_frame (const framepos_t& f, const framecnt_t& frame_rate) const
 {
 
-	if (_type == Constant) {
+	if (_type == Constant || _c_func == 0.0) {
 		return pulses_per_minute();
 	}
 
@@ -213,7 +213,7 @@ TempoSection::tempo_at_frame (const framepos_t& f, const framecnt_t& frame_rate)
 framepos_t
 TempoSection::frame_at_tempo (const double& ppm, const double& b, const framecnt_t& frame_rate) const
 {
-	if (_type == Constant) {
+	if (_type == Constant || _c_func == 0.0) {
 		return ((b - pulse())  * frames_per_pulse (frame_rate))  + frame();
 	}
 
@@ -225,7 +225,7 @@ double
 TempoSection::tempo_at_pulse (const double& p) const
 {
 
-	if (_type == Constant) {
+	if (_type == Constant || _c_func == 0.0) {
 		return pulses_per_minute();
 	}
 	double const ppm = pulse_tempo_at_pulse (p - pulse());
@@ -239,7 +239,7 @@ TempoSection::tempo_at_pulse (const double& p) const
 double
 TempoSection::pulse_at_tempo (const double& ppm, const framepos_t& f, const framecnt_t& frame_rate) const
 {
-	if (_type == Constant) {
+	if (_type == Constant || _c_func == 0.0) {
 		double const pulses = ((f - frame()) / frames_per_pulse (frame_rate)) + pulse();
 		return  pulses;
 	}
@@ -253,7 +253,7 @@ TempoSection::pulse_at_tempo (const double& ppm, const framepos_t& f, const fram
 double
 TempoSection::pulse_at_frame (const framepos_t& f, const framecnt_t& frame_rate) const
 {
-	if (_type == Constant) {
+	if (_type == Constant || _c_func == 0.0) {
 		return ((f - frame()) / frames_per_pulse (frame_rate)) + pulse();
 	}
 
@@ -268,7 +268,7 @@ TempoSection::pulse_at_frame (const framepos_t& f, const framecnt_t& frame_rate)
 framepos_t
 TempoSection::frame_at_pulse (const double& p, const framecnt_t& frame_rate) const
 {
-	if (_type == Constant) {
+	if (_type == Constant || _c_func == 0.0) {
 		return (framepos_t) floor ((p - pulse()) * frames_per_pulse (frame_rate)) + frame();
 	}
 
@@ -885,51 +885,61 @@ TempoMap::replace_tempo (const TempoSection& ts, const Tempo& tempo, const frame
 	PropertyChanged (PropertyChange ());
 }
 
-void
+TempoSection*
 TempoMap::add_tempo (const Tempo& tempo, const double& pulse, ARDOUR::TempoSection::Type type)
 {
+	TempoSection* ts = 0;
 	{
 		Glib::Threads::RWLock::WriterLock lm (lock);
-		add_tempo_locked (tempo, pulse, true, type);
+		ts = add_tempo_locked (tempo, pulse, true, type);
 	}
 
 	PropertyChanged (PropertyChange ());
+
+	return ts;
 }
 
-void
+TempoSection*
 TempoMap::add_tempo (const Tempo& tempo, const framepos_t& frame, ARDOUR::TempoSection::Type type)
 {
+	TempoSection* ts = 0;
 	{
 		Glib::Threads::RWLock::WriterLock lm (lock);
-		add_tempo_locked (tempo, frame, true, type);
+		ts = add_tempo_locked (tempo, frame, true, type);
 	}
 
 
 	PropertyChanged (PropertyChange ());
+
+	return ts;
 }
 
-void
+TempoSection*
 TempoMap::add_tempo_locked (const Tempo& tempo, double pulse, bool recompute, ARDOUR::TempoSection::Type type)
 {
-	TempoSection* ts = new TempoSection (pulse, tempo.beats_per_minute(), tempo.note_type(), type);
+	TempoSection* t = new TempoSection (pulse, tempo.beats_per_minute(), tempo.note_type(), type);
 
-	do_insert (ts);
+	do_insert (t);
 
 	if (recompute) {
-		solve_map (_metrics, ts, ts->pulse());
+		solve_map (_metrics, t, t->pulse());
 	}
+
+	return t;
 }
 
-void
+TempoSection*
 TempoMap::add_tempo_locked (const Tempo& tempo, framepos_t frame, bool recompute, ARDOUR::TempoSection::Type type)
 {
-	TempoSection* ts = new TempoSection (frame, tempo.beats_per_minute(), tempo.note_type(), type);
+	TempoSection* t = new TempoSection (frame, tempo.beats_per_minute(), tempo.note_type(), type);
 
-	do_insert (ts);
+	do_insert (t);
 
 	if (recompute) {
-		solve_map (_metrics, ts, ts->frame());
+		solve_map (_metrics, t, t->frame());
 	}
+
+	return t;
 }
 
 void
@@ -1058,7 +1068,6 @@ TempoMap::add_meter_locked (const Meter& meter, double beat, BBT_Time where, boo
 MeterSection*
 TempoMap::add_meter_locked (const Meter& meter, framepos_t frame, double beat, Timecode::BBT_Time where, bool recompute)
 {
-
 	MeterSection* new_meter = new MeterSection (frame, beat, where, meter.divisions_per_bar(), meter.note_divisor());
 
 	double pulse = pulse_at_frame_locked (_metrics, frame);
@@ -1236,6 +1245,11 @@ TempoMap::recompute_tempos (Metrics& metrics)
 			if (!t->active()) {
 				continue;
 			}
+			if (!t->movable()) {
+				t->set_pulse (0.0);
+				prev_t = t;
+				continue;
+			}
 			if (prev_t) {
 				if (t->position_lock_style() == AudioTime) {
 					prev_t->set_c_func (prev_t->compute_c_func_frame (t->pulses_per_minute(), t->frame(), _frame_rate));
@@ -1729,8 +1743,8 @@ TempoMap::check_solved (Metrics& metrics, bool by_frame)
 					return false;
 				}
 
-				/* precision check ensures pulses and frames align independent of lock style.*/
-				if (by_frame && t->frame() != prev_t->frame_at_pulse (t->pulse(), _frame_rate)) {
+				/* precision check ensures pulses and frames align.*/
+				if (t->frame() != prev_t->frame_at_pulse (t->pulse(), _frame_rate)) {
 					return false;
 				}
 			}
@@ -1782,9 +1796,9 @@ TempoMap::solve_map (Metrics& imaginary, TempoSection* section, const framepos_t
 	}
 	if (section->movable() && frame <= first_m_frame) {
 		return false;
-	} else {
-		section->set_active (true);
 	}
+
+	section->set_active (true);
 	section->set_frame (frame);
 
 	for (Metrics::iterator i = imaginary.begin(); i != imaginary.end(); ++i) {
@@ -1840,11 +1854,12 @@ TempoMap::solve_map (Metrics& imaginary, TempoSection* section, const framepos_t
 	} else {
 		recompute_tempos (imaginary);
 	}
+
 	if (check_solved (imaginary, true)) {
 		recompute_meters (imaginary);
 		return true;
 	}
-
+#if (0)
 	MetricSectionSorter cmp;
 	imaginary.sort (cmp);
 	if (section->position_lock_style() == MusicTime) {
@@ -1855,10 +1870,12 @@ TempoMap::solve_map (Metrics& imaginary, TempoSection* section, const framepos_t
 	} else {
 		recompute_tempos (imaginary);
 	}
+
 	if (check_solved (imaginary, true)) {
 		recompute_meters (imaginary);
 		return true;
 	}
+#endif
 	//dump (imaginary, std::cerr);
 
 	return false;
@@ -1878,6 +1895,11 @@ TempoMap::solve_map (Metrics& imaginary, TempoSection* section, const double& pu
 			if (!t->active()) {
 				continue;
 			}
+			if (!t->movable()) {
+				t->set_pulse (0.0);
+				prev_t = t;
+				continue;
+			}
 			if (prev_t) {
 				if (t == section) {
 					section_prev = prev_t;
@@ -1907,6 +1929,7 @@ TempoMap::solve_map (Metrics& imaginary, TempoSection* section, const double& pu
 	} else {
 		recompute_tempos (imaginary);
 	}
+
 	if (check_solved (imaginary, false)) {
 		recompute_meters (imaginary);
 		return true;
@@ -2121,22 +2144,24 @@ TempoMap::solve_map (Metrics& imaginary, MeterSection* section, const double& pu
 }
 
 /** places a copy of _metrics into copy and returns a pointer
- *  to section's equivalent.
+ *  to section's equivalent in copy.
  */
 TempoSection*
 TempoMap::copy_metrics_and_point (Metrics& copy, TempoSection* section)
 {
 	TempoSection* t;
-	TempoSection* ret = 0;
 	MeterSection* m;
+	TempoSection* ret = 0;
 
 	for (Metrics::iterator i = _metrics.begin(); i != _metrics.end(); ++i) {
 		if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
 			if (t == section) {
 				if (t->position_lock_style() == MusicTime) {
 					ret = new TempoSection (t->pulse(), t->beats_per_minute(), t->note_type(), t->type());
+					ret->set_frame (t->frame());
 				} else {
 					ret = new TempoSection (t->frame(), t->beats_per_minute(), t->note_type(), t->type());
+					ret->set_pulse (t->pulse());
 				}
 				ret->set_active (t->active());
 				ret->set_movable (t->movable());
@@ -2146,8 +2171,10 @@ TempoMap::copy_metrics_and_point (Metrics& copy, TempoSection* section)
 			TempoSection* cp = 0;
 			if (t->position_lock_style() == MusicTime) {
 				cp = new TempoSection (t->pulse(), t->beats_per_minute(), t->note_type(), t->type());
+				cp->set_frame (t->frame());
 			} else {
 				cp = new TempoSection (t->frame(), t->beats_per_minute(), t->note_type(), t->type());
+				cp->set_pulse (t->pulse());
 			}
 			cp->set_active (t->active());
 			cp->set_movable (t->movable());
@@ -2166,7 +2193,7 @@ TempoMap::copy_metrics_and_point (Metrics& copy, TempoSection* section)
 			copy.push_back (cp);
 		}
 	}
-	//recompute_map (copy);
+
 	return ret;
 }
 
@@ -2210,6 +2237,7 @@ TempoMap::predict_tempo_frame (TempoSection* section, const BBT_Time& bbt)
 	TempoSection* new_section = copy_metrics_and_point (future_map, section);
 
 	const double beat = bbt_to_beats_locked (future_map, bbt);
+
 	if (solve_map (future_map, new_section, pulse_at_beat_locked (future_map, beat))) {
 		ret = new_section->frame();
 	} else {
@@ -2347,10 +2375,8 @@ TempoMap::bbt_duration_at (framepos_t pos, const BBT_Time& bbt, int dir)
 	const double tick_at_time = beat_at_frame_locked (_metrics, pos) * BBT_Time::ticks_per_beat;
 	const double bbt_ticks = bbt.ticks + (bbt.beats * BBT_Time::ticks_per_beat);
 	const double total_beats = (tick_at_time + bbt_ticks) / BBT_Time::ticks_per_beat;
-	const framecnt_t time_at_bbt = frame_at_beat_locked (_metrics, total_beats);
-	const framecnt_t ret = time_at_bbt;
 
-	return ret;
+	return frame_at_beat_locked (_metrics, total_beats);
 }
 
 framepos_t
@@ -2679,8 +2705,8 @@ TempoMap::tempo_at_locked (const framepos_t& frame) const
 			}
 			if ((prev_t) && t->frame() > frame) {
 				/* t is the section past frame */
-				const double ret = prev_t->tempo_at_frame (frame, _frame_rate) * prev_t->note_type();
-				const Tempo ret_tempo (ret, prev_t->note_type());
+				const double ret_bpm = prev_t->tempo_at_frame (frame, _frame_rate) * prev_t->note_type();
+				const Tempo ret_tempo (ret_bpm, prev_t->note_type());
 				return ret_tempo;
 			}
 			prev_t = t;
@@ -2703,7 +2729,6 @@ TempoMap::meter_section_at (framepos_t frame) const
 const MeterSection&
 TempoMap::meter_section_at_locked (framepos_t frame) const
 {
-	//framepos_t const frame_off = frame + frame_offset_at (_metrics, frame);
 	Metrics::const_iterator i;
 	MeterSection* prev = 0;