big rework of scrolling, horizontal part considered almost 100% done.

Many more changes than I would typically like in a single commit, but this was all very intertwined.
Vertical scrolling using track-stepping still to follow.

8 files changed, 262 insertions, 238 deletions

diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index 2c3babb9c8..d0664b09ad 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -313,10 +313,8 @@ Editor::Editor ()
 	bbt_beat_subdivision = 4;
 	_visible_canvas_width = 0;
 	_visible_canvas_height = 0;
-	last_autoscroll_x = 0;
-	last_autoscroll_y = 0;
-	autoscroll_active = false;
-	autoscroll_timeout_tag = -1;
+	autoscroll_horizontal_allowed = false;
+	autoscroll_vertical_allowed = false;
 	logo_item = 0;
 
 	analysis_window = 0;
@@ -4291,35 +4289,45 @@ Editor::idle_visual_changer ()
 	pending_visual_change.idle_handler_id = -1;
 	pending_visual_change.being_handled = true;
 	
-	VisualChange::Type p = pending_visual_change.pending;
+	VisualChange vc = pending_visual_change;
+
 	pending_visual_change.pending = (VisualChange::Type) 0;
 
-	double const last_time_origin = horizontal_position ();
+	visual_changer (vc);
 
+	pending_visual_change.being_handled = false;
 
-	if (p & VisualChange::ZoomLevel) {
-		set_samples_per_pixel (pending_visual_change.samples_per_pixel);
+	return 0; /* this is always a one-shot call */
+}
+
+void
+Editor::visual_changer (const VisualChange& vc)
+{
+	double const last_time_origin = horizontal_position ();
+
+	if (vc.pending & VisualChange::ZoomLevel) {
+		set_samples_per_pixel (vc.samples_per_pixel);
 
 		compute_fixed_ruler_scale ();
 
 		ARDOUR::TempoMap::BBTPointList::const_iterator current_bbt_points_begin;
 		ARDOUR::TempoMap::BBTPointList::const_iterator current_bbt_points_end;
 		
-		compute_current_bbt_points (pending_visual_change.time_origin, pending_visual_change.time_origin + current_page_samples(),
+		compute_current_bbt_points (vc.time_origin, pending_visual_change.time_origin + current_page_samples(),
 					    current_bbt_points_begin, current_bbt_points_end);
-		compute_bbt_ruler_scale (pending_visual_change.time_origin, pending_visual_change.time_origin + current_page_samples(),
+		compute_bbt_ruler_scale (vc.time_origin, pending_visual_change.time_origin + current_page_samples(),
 					 current_bbt_points_begin, current_bbt_points_end);
 		update_tempo_based_rulers (current_bbt_points_begin, current_bbt_points_end);
 
 		update_video_timeline();
 	}
 
-	if (p & VisualChange::TimeOrigin) {
-		set_horizontal_position (pending_visual_change.time_origin / samples_per_pixel);
+	if (vc.pending & VisualChange::TimeOrigin) {
+		set_horizontal_position (vc.time_origin / samples_per_pixel);
 	}
 
-	if (p & VisualChange::YOrigin) {
-		vertical_adjustment.set_value (pending_visual_change.y_origin);
+	if (vc.pending & VisualChange::YOrigin) {
+		vertical_adjustment.set_value (vc.y_origin);
 	}
 
 	if (last_time_origin == horizontal_position ()) {
@@ -4328,14 +4336,11 @@ Editor::idle_visual_changer ()
 		redisplay_tempo (true);
 	}
 
-	if (!(p & VisualChange::ZoomLevel)) {
+	if (!(vc.pending & VisualChange::ZoomLevel)) {
 		update_video_timeline();
 	}
 
 	_summary->set_overlays_dirty ();
-
-	pending_visual_change.being_handled = false;
-	return 0; /* this is always a one-shot call */
 }
 
 struct EditorOrderTimeAxisSorter {
diff --git a/gtk2_ardour/editor.h b/gtk2_ardour/editor.h
index b1edb26737..bf52948b4b 100644
--- a/gtk2_ardour/editor.h
+++ b/gtk2_ardour/editor.h
@@ -207,7 +207,7 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 	   account any scrolling offsets.
 	*/
 
-	framepos_t pixel_to_sample (double pixel) const {
+	framepos_t pixel_to_sample_from_event (double pixel) const {
 
 		/* pixel can be less than zero when motion events
 		   are processed. since we've already run the world->canvas
@@ -222,6 +222,10 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 		}
 	}
 
+	framepos_t pixel_to_sample (double pixel) const {
+		return pixel * samples_per_pixel;
+	}
+
         double sample_to_pixel (framepos_t sample) const {
 		return sample / samples_per_pixel;
 	}
@@ -408,7 +412,8 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 		return _drags;
 	}
 
-	void maybe_autoscroll (bool, bool, bool, bool);
+        void maybe_autoscroll (bool, bool, bool);
+        bool autoscroll_active() const;
 
 	Gdk::Cursor* get_canvas_cursor () const { return current_canvas_cursor; }
 	void set_canvas_cursor (Gdk::Cursor*, bool save=false);
@@ -1022,6 +1027,7 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 
 	static int _idle_visual_changer (void *arg);
 	int idle_visual_changer ();
+        void visual_changer (const VisualChange&);
 	void ensure_visual_change_idle_handler ();
 
 	/* track views */
@@ -1072,8 +1078,6 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
         Gtkmm2ext::ActionMap editor_action_map;
         Gtkmm2ext::Bindings  key_bindings;
 
-	int ensure_cursor (framepos_t* pos);
-
 	void cut_copy (Editing::CutCopyOp);
 	bool can_cut_copy () const;
 	void cut_copy_points (Editing::CutCopyOp);
@@ -1722,22 +1726,15 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 
 	/* autoscrolling */
 
-	bool autoscroll_active;
-	int autoscroll_timeout_tag;
-	int autoscroll_x;
-	int autoscroll_y;
-	int last_autoscroll_x;
-	int last_autoscroll_y;
-	uint32_t autoscroll_cnt;
-	framecnt_t autoscroll_x_distance;
-	double autoscroll_y_distance;
-
-	bool _autoscroll_fudging;
-	int autoscroll_fudge_threshold () const;
+        sigc::connection autoscroll_connection;
+        bool autoscroll_horizontal_allowed;
+        bool autoscroll_vertical_allowed;
+        uint32_t autoscroll_cnt;
+        Gtk::Widget* autoscroll_widget;
+        ArdourCanvas::Rect autoscroll_boundary;
 
-	static gint _autoscroll_canvas (void *);
 	bool autoscroll_canvas ();
-	void start_canvas_autoscroll (int x, int y);
+        void start_canvas_autoscroll (bool allow_horiz, bool allow_vert);
 	void stop_canvas_autoscroll ();
 
 	/* trimming */
diff --git a/gtk2_ardour/editor_canvas.cc b/gtk2_ardour/editor_canvas.cc
index 971e728db6..a4927192fe 100644
--- a/gtk2_ardour/editor_canvas.cc
+++ b/gtk2_ardour/editor_canvas.cc
@@ -450,245 +450,291 @@ Editor::drop_paths (const RefPtr<Gdk::DragContext>& context,
 	context->drag_finish (true, false, time);
 }
 
-/** If the editor window is arranged such that the edge of the trackview is right up
- *  against the edge of the screen, autoscroll will not work very well.  In this situation,
- *  we start autoscrolling some distance in from the right-hand-side of the screen edge;
- *  this is the distance at which that happens.
- */
-int
-Editor::autoscroll_fudge_threshold () const
-{
-	return current_page_samples() / 6;
-}
-
 /** @param allow_horiz true to allow horizontal autoscroll, otherwise false.
  *
  *  @param allow_vert true to allow vertical autoscroll, otherwise false.
  *
- *  @param moving_left true if we are moving left, so we only want to autoscroll on the left of the canvas,
- *  otherwise false, so we only want to autoscroll on the right of the canvas.
- *
- *  @param moving_up true if we are moving up, so we only want to autoscroll at the top of the canvas,
- *  otherwise false, so we only want to autoscroll at the bottom of the canvas.
  */
 void
-Editor::maybe_autoscroll (bool allow_horiz, bool allow_vert, bool moving_left, bool moving_up)
+Editor::maybe_autoscroll (bool allow_horiz, bool allow_vert, bool from_headers)
 {
 	if (!Config->get_autoscroll_editor ()) {
 		return;
 	}
-	
-	bool startit = false;
-
-	/* Work out the distance between the right hand edge of the trackview and the edge of
-	   the monitor that it is on.
-	*/
-
-	Glib::RefPtr<Gdk::Window> gdk_window = get_window ();
-	Gdk::Rectangle window_rect;
-	gdk_window->get_frame_extents (window_rect);
-	
-	Glib::RefPtr<Gdk::Screen> screen = get_screen ();
-	Gdk::Rectangle root_rect;
-	screen->get_root_window()->get_frame_extents (root_rect);
-
-	Gtk::Allocation editor_list = _the_notebook.get_allocation ();
-
-	framecnt_t distance = pixel_to_sample (root_rect.get_x() + root_rect.get_width() - window_rect.get_x() - window_rect.get_width());
-	if (_the_notebook.is_visible ()) {
-		distance += pixel_to_sample (editor_list.get_width());
-	}
-
-	/* Note whether we're fudging the autoscroll (see autoscroll_fudge_threshold) */
-	_autoscroll_fudging = (distance < autoscroll_fudge_threshold ());
 
-	/* ty is in canvas-coordinate space */
+	if (autoscroll_boundary.empty()) {
 
-	double const ty = _drags->current_pointer_y();
-	ArdourCanvas::Rect visible = _track_canvas->visible_area();
-
-	autoscroll_y = 0;
-	autoscroll_x = 0;
-	if (ty < visible.y0 && moving_up && allow_vert) {
-		autoscroll_y = -1;
-		startit = true;
-	} else if (ty > visible.y1 && !moving_up && allow_vert) {
-		autoscroll_y = 1;
-		startit = true;
-	}
+		ArdourCanvas::Rect scrolling_boundary;
+		Gtk::Allocation alloc;
+		
+		if (from_headers) {
+			alloc = controls_layout.get_allocation ();
+		} else {
+			alloc = _track_canvas_viewport->get_allocation ();
 
-	framepos_t rightmost_frame = leftmost_frame + current_page_samples();
-	if (_autoscroll_fudging) {
-		rightmost_frame -= autoscroll_fudge_threshold ();
-	}
+			/* Increase the autoscroll area to include the rulers.
+			   
+			   XXX this can go away once the two canvases are
+			   unified.
+			*/
+			
+			Gdk::Rectangle timebars = time_canvas_event_box.get_allocation ();
+			alloc.set_y (timebars.get_y());
+			alloc.set_height (alloc.get_height() + timebars.get_height());
+			
+			/* if there is no other widget on the right side of
+			   the canvas, reduce the effective width of
+			   the autoscroll boundary so that we start scrolling
+			   before we hit the edge.
+
+			   this helps when the window is slammed up against
+			   the right edge of the screen, making it hard to 
+			   scroll effectively.
+			*/
 
-	if (_drags->current_pointer_frame() > rightmost_frame && allow_horiz) {
-		if (rightmost_frame < max_framepos && !moving_left) {
-			autoscroll_x = 1;
-			startit = true;
-		}
-	} else if (_drags->current_pointer_frame() < leftmost_frame && allow_horiz) {
-		if (leftmost_frame > 0 && moving_left) {
-			autoscroll_x = -1;
-			startit = true;
+			if (alloc.get_width() > 10) { 
+				alloc.set_width (alloc.get_width() - 10);
+			} 
 		}
+		
+		autoscroll_boundary = ArdourCanvas::Rect (alloc.get_x(), alloc.get_y(), 
+							  alloc.get_x() + alloc.get_width(), 
+							  alloc.get_y() + alloc.get_height());
 	}
 
-	if (autoscroll_active && ((autoscroll_x != last_autoscroll_x) || (autoscroll_y != last_autoscroll_y) || (autoscroll_x == 0 && autoscroll_y == 0))) {
-		stop_canvas_autoscroll ();
-	}
+	int x, y;
+	Gdk::ModifierType mask;
 
-	if (startit && autoscroll_timeout_tag < 0) {
-		start_canvas_autoscroll (autoscroll_x, autoscroll_y);
-	}
+	get_window()->get_pointer (x, y, mask);
 
-	last_autoscroll_x = autoscroll_x;
-	last_autoscroll_y = autoscroll_y;
+	if (!autoscroll_boundary.contains (ArdourCanvas::Duple (x, y))) {
+		if (!autoscroll_active()) {
+			start_canvas_autoscroll (allow_horiz, allow_vert);
+		}
+	} 
 }
 
-gint
-Editor::_autoscroll_canvas (void *arg)
+bool
+Editor::autoscroll_active () const
 {
-        return ((Editor *) arg)->autoscroll_canvas ();
+	return autoscroll_connection.connected ();
 }
 
 bool
 Editor::autoscroll_canvas ()
 {
-	framepos_t new_frame;
-	framepos_t limit = max_framepos - current_page_samples();
-	double new_pixel;
+	int x, y;
+	Gdk::ModifierType mask;
+	frameoffset_t dx = 0;
+	double dy = 0;
+	bool no_stop = false;
+
+	get_window()->get_pointer (x, y, mask);
+
+	VisualChange vc;
+
+	if (autoscroll_horizontal_allowed) {
+
+		framepos_t new_frame = leftmost_frame;
 
-	if (autoscroll_x_distance != 0) {
+		/* horizontal */
 
-		if (autoscroll_x > 0) {
-			autoscroll_x_distance = (_drags->current_pointer_frame() - (leftmost_frame + current_page_samples())) / 3;
-			if (_autoscroll_fudging) {
-				autoscroll_x_distance += autoscroll_fudge_threshold () / 3;
+		if (x > autoscroll_boundary.x1) {
+
+			/* bring it back into view */
+			dx = x - autoscroll_boundary.x1;
+			dx += 10 + (2 * (autoscroll_cnt/2));
+
+			dx = pixel_to_sample (dx);
+
+			if (leftmost_frame < max_framepos - dx) {
+				new_frame = leftmost_frame + dx;
+			} else {
+				new_frame = max_framepos;
 			}
-		} else if (autoscroll_x < 0) {
-			autoscroll_x_distance = (leftmost_frame - _drags->current_pointer_frame()) / 3;
 
-		}
-	}
+			no_stop = true;
 
-	if (autoscroll_y_distance != 0) {
-		if (autoscroll_y > 0) {
-			autoscroll_y_distance = (_drags->current_pointer_y() - _visible_canvas_height) / 3;
-		} else if (autoscroll_y < 0) {
+		} else if (x < autoscroll_boundary.x0) {
+			
+			dx = autoscroll_boundary.x0 - x;
+			dx += 10 + (2 * (autoscroll_cnt/2));
 
-			autoscroll_y_distance = (vertical_adjustment.get_value () - _drags->current_pointer_y()) / 3;
+			dx = pixel_to_sample (dx);
+
+			if (leftmost_frame >= dx) {
+				new_frame = leftmost_frame - dx;
+			} else {
+				new_frame = 0;
+			}
+
+			no_stop = true;
+		}
+		
+		if (new_frame != leftmost_frame) {
+			vc.time_origin = new_frame;
+			vc.add (VisualChange::TimeOrigin);
 		}
 	}
 
-	if (autoscroll_x < 0) {
-		if (leftmost_frame < autoscroll_x_distance) {
-			new_frame = 0;
-		} else {
-			new_frame = leftmost_frame - autoscroll_x_distance;
+	if (autoscroll_vertical_allowed) {
+		
+		const double vertical_pos = vertical_adjustment.get_value();
+		double new_pixel = vertical_pos;
+
+		/* vertical */ 
+		
+		new_pixel = vertical_pos;
+		
+		if (y < autoscroll_boundary.y0) {
+
+			/* scroll to make higher tracks visible */
+
+			const int step_size = _visible_canvas_height / 100;
+
+			dy = autoscroll_boundary.y0 - y;
+			dy += step_size + (step_size * (autoscroll_cnt/10));
+
+			if (vertical_pos > dy) {
+				new_pixel = vertical_pos - dy;
+			} else {
+				new_pixel = 0;
+			}
+
+			no_stop = true;
+
+		} else if (y > autoscroll_boundary.y1) {
+
+			/* scroll to make lower tracks visible */
+
+			const int step_size = _visible_canvas_height / 100;
+
+			dy = y - autoscroll_boundary.y1;
+			dy +=  step_size + (step_size * (autoscroll_cnt/10));
+
+			/* unlike horizontally, we never want to scroll past the lower edge of the full canvas as defined by all visible tracks
+			 */
+			new_pixel = min (_full_canvas_height - _visible_canvas_height, min (_full_canvas_height, vertical_pos + dy));
+			/* adjust dy to match */
+			dy = vertical_pos - new_pixel; 
+
+			no_stop = true;
 		}
- 	} else if (autoscroll_x > 0) {
-		if (leftmost_frame > limit - autoscroll_x_distance) {
-			new_frame = limit;
-		} else {
-			new_frame = leftmost_frame + autoscroll_x_distance;
+		
+		if (new_pixel != vertical_pos) {
+			vc.add (VisualChange::YOrigin);
+			vc.y_origin = new_pixel;
 		}
-	} else {
-		new_frame = leftmost_frame;
 	}
 
-	double vertical_pos = vertical_adjustment.get_value();
+	if (vc.pending) {
 
-	if (autoscroll_y < 0) {
+		/* change horizontal & vertical position first */
 
-		if (vertical_pos < autoscroll_y_distance) {
-			new_pixel = 0;
-		} else {
-			new_pixel = vertical_pos - autoscroll_y_distance;
-		}
+		visual_changer (vc);
 
- 	} else if (autoscroll_y > 0) {
+		/* now send a motion event to notify anyone who cares
+		   that we have moved to a new location (because we scrolled)
+		*/
 
-		new_pixel = min (_full_canvas_height - _visible_canvas_height, min (_full_canvas_height, (vertical_adjustment.get_value() + autoscroll_y_distance)));
+		GdkEventMotion ev;
 
-	} else {
-		new_pixel = vertical_pos;
-	}
+		ev.type = GDK_MOTION_NOTIFY;
+		ev.state = Gdk::BUTTON1_MASK;
+		
+		/* the motion handler expects events in canvas coordinate space */
 
-	if ((new_frame == 0 || new_frame == limit) && (new_pixel == 0 || new_pixel == DBL_MAX)) {
-		/* we are done */
-		return false;
-	}
+		/* first convert from Editor window coordinates to canvas
+		 * window coordinates
+		 */
 
-	if (new_frame != leftmost_frame) {
-		reset_x_origin (new_frame);
-	}
+		int cx;
+		int cy;
 
-	if (new_pixel != vertical_pos) {
-		vertical_adjustment.set_value (new_pixel);
-	}
+		/* clamp x and y to remain within the visible area */
 
-	/* fake an event. */
+		x = min (max ((ArdourCanvas::Coord) x, autoscroll_boundary.x0), autoscroll_boundary.x1);
+		y = min (max ((ArdourCanvas::Coord) y, autoscroll_boundary.y0), autoscroll_boundary.y1);
 
-	Glib::RefPtr<Gdk::Window> canvas_window = const_cast<Editor*>(this)->_track_canvas->get_window();
-	gint x, y;
-	Gdk::ModifierType mask;
-	GdkEventMotion ev;
-	canvas_window->get_pointer (x, y, mask);
-	ev.type = GDK_MOTION_NOTIFY;
-	ev.state = Gdk::BUTTON1_MASK;
+		translate_coordinates (*_track_canvas_viewport, x, y, cx, cy);
 
-	/* the motion handler expects events in canvas coordinate space */
-	ArdourCanvas::Duple d = _track_canvas->window_to_canvas (ArdourCanvas::Duple (x, y));
-	ev.x = d.x;
-	ev.y = d.y;
+		ArdourCanvas::Duple d = _track_canvas->window_to_canvas (ArdourCanvas::Duple (cx, cy));
+		ev.x = d.x;
+		ev.y = d.y;
 
-	motion_handler (0, (GdkEvent*) &ev, true);
+		motion_handler (0, (GdkEvent*) &ev, true);
 
-	autoscroll_cnt++;
+	} else if (no_stop) {
 
-	if (autoscroll_cnt == 1) {
+		/* not changing visual state but pointer is outside the scrolling boundary
+		 * so we still need to deliver a fake motion event 
+		 */
 
-		/* connect the timeout so that we get called repeatedly */
+		GdkEventMotion ev;
 
-		autoscroll_timeout_tag = g_idle_add ( _autoscroll_canvas, this);
-		return false;
+		ev.type = GDK_MOTION_NOTIFY;
+		ev.state = Gdk::BUTTON1_MASK;
+		
+		/* the motion handler expects events in canvas coordinate space */
+
+		/* first convert from Editor window coordinates to canvas
+		 * window coordinates
+		 */
+
+		int cx;
+		int cy;
+
+		/* clamp x and y to remain within the visible area */
+
+		x = min (max ((ArdourCanvas::Coord) x, autoscroll_boundary.x0), autoscroll_boundary.x1);
+		y = min (max ((ArdourCanvas::Coord) y, autoscroll_boundary.y0), autoscroll_boundary.y1);
+
+		translate_coordinates (*_track_canvas_viewport, x, y, cx, cy);
+
+		ArdourCanvas::Duple d = _track_canvas->window_to_canvas (ArdourCanvas::Duple (cx, cy));
+		ev.x = d.x;
+		ev.y = d.y;
 
+		motion_handler (0, (GdkEvent*) &ev, true);
+
+	} else {
+		stop_canvas_autoscroll ();
+		autoscroll_boundary = ArdourCanvas::Rect();
+		return false;
 	}
 
-	return true;
-}
+	autoscroll_cnt++;
+
+	return true; /* call me again */
+}	
 
 void
-Editor::start_canvas_autoscroll (int dx, int dy)
+Editor::start_canvas_autoscroll (bool allow_horiz, bool allow_vert)
 {
-	if (!_session || autoscroll_active) {
+	if (!_session) {
 		return;
 	}
 
 	stop_canvas_autoscroll ();
 
-	autoscroll_active = true;
-	autoscroll_x = dx;
-	autoscroll_y = dy;
-	autoscroll_x_distance = (framepos_t) floor (current_page_samples()/50.0);
-	autoscroll_y_distance = fabs ((double)dy * 5); /* pixels */
 	autoscroll_cnt = 0;
+	autoscroll_horizontal_allowed = allow_horiz;
+	autoscroll_vertical_allowed = allow_vert;
 
-	/* do it right now, which will start the repeated callbacks */
+	/* do the first scroll right now
+	*/
 
 	autoscroll_canvas ();
+
+	/* scroll again at very very roughly 30FPS */
+
+	autoscroll_connection = Glib::signal_timeout().connect (sigc::mem_fun (*this, &Editor::autoscroll_canvas), 30);
 }
 
 void
 Editor::stop_canvas_autoscroll ()
 {
-	if (autoscroll_timeout_tag >= 0) {
-		g_source_remove (autoscroll_timeout_tag);
-		autoscroll_timeout_tag = -1;
-	}
-
-	autoscroll_active = false;
+	autoscroll_connection.disconnect ();
 }
 
 bool
@@ -750,8 +796,6 @@ Editor::set_horizontal_position (double p)
 	}
 
 	update_video_timeline();
-
-	HorizontalPositionChanged (); /* EMIT SIGNAL */
 }
 
 void
diff --git a/gtk2_ardour/editor_drag.cc b/gtk2_ardour/editor_drag.cc
index 56879fbaa0..7d9e7e373c 100644
--- a/gtk2_ardour/editor_drag.cc
+++ b/gtk2_ardour/editor_drag.cc
@@ -361,16 +361,16 @@ Drag::motion_handler (GdkEvent* event, bool from_autoscroll)
 
 		if (event->motion.state & Gdk::BUTTON1_MASK || event->motion.state & Gdk::BUTTON2_MASK) {
 			if (!from_autoscroll) {
-				bool const moving_left = _drags->current_pointer_x() < _last_pointer_x;
-				bool const moving_up = _drags->current_pointer_y() < _last_pointer_y;
-				_editor->maybe_autoscroll (true, allow_vertical_autoscroll (), moving_left, moving_up);
+				_editor->maybe_autoscroll (true, allow_vertical_autoscroll (), false);
 			}
 
-			motion (event, _move_threshold_passed != old_move_threshold_passed);
-
-			_last_pointer_x = _drags->current_pointer_x ();
-			_last_pointer_y = _drags->current_pointer_y ();
-			_last_pointer_frame = adjusted_current_frame (event);
+			if (!_editor->autoscroll_active() || from_autoscroll) {
+				motion (event, _move_threshold_passed != old_move_threshold_passed);
+				
+				_last_pointer_x = _drags->current_pointer_x ();
+				_last_pointer_y = _drags->current_pointer_y ();
+				_last_pointer_frame = adjusted_current_frame (event);
+			}
 
 			return true;
 		}
diff --git a/gtk2_ardour/editor_mouse.cc b/gtk2_ardour/editor_mouse.cc
index 0a8ef4296b..b0ae055aa8 100644
--- a/gtk2_ardour/editor_mouse.cc
+++ b/gtk2_ardour/editor_mouse.cc
@@ -179,12 +179,12 @@ Editor::canvas_event_sample (GdkEvent const * event, double* pcx, double* pcy) c
 		*pcy = y;
 	}
 
-	/* note that pixel_to_sample() never returns less than zero, so even if the pixel
+	/* note that pixel_to_sample_from_event() never returns less than zero, so even if the pixel
 	   position is negative (as can be the case with motion events in particular),
 	   the frame location is always positive.
 	*/
 
-	return pixel_to_sample (x);
+	return pixel_to_sample_from_event (x);
 }
 
 Gdk::Cursor*
diff --git a/gtk2_ardour/public_editor.h b/gtk2_ardour/public_editor.h
index 8e673a7824..d2f0f9c49b 100644
--- a/gtk2_ardour/public_editor.h
+++ b/gtk2_ardour/public_editor.h
@@ -303,8 +303,6 @@ class PublicEditor : public Gtk::Window, public PBD::StatefulDestructible, publi
 	virtual void get_equivalent_regions (RegionView* rv, std::vector<RegionView*>&, PBD::PropertyID) const = 0;
 
 	sigc::signal<void> ZoomChanged;
-	/** Emitted when the horizontal position of the editor view changes */
-	sigc::signal<void> HorizontalPositionChanged;
 	sigc::signal<void> Realized;
 	sigc::signal<void,framepos_t> UpdateAllTransportClocks;
 
@@ -382,8 +380,9 @@ class PublicEditor : public Gtk::Window, public PBD::StatefulDestructible, publi
 	virtual Gtkmm2ext::TearOff* tools_tearoff () const = 0;
 
 	virtual DragManager* drags () const = 0;
-	virtual void maybe_autoscroll (bool, bool, bool, bool) = 0;
+        virtual void maybe_autoscroll (bool, bool, bool from_headers) = 0;
 	virtual void stop_canvas_autoscroll () = 0;
+        virtual bool autoscroll_active() const = 0;
 
 	virtual MouseCursors const * cursors () const = 0;
 	virtual VerboseCursor * verbose_cursor () const = 0;
diff --git a/gtk2_ardour/time_axis_view.cc b/gtk2_ardour/time_axis_view.cc
index 036323627c..d373d3f31b 100644
--- a/gtk2_ardour/time_axis_view.cc
+++ b/gtk2_ardour/time_axis_view.cc
@@ -370,32 +370,11 @@ TimeAxisView::controls_ebox_motion (GdkEventMotion* ev)
 		 * are pretending that the drag is taking place over the canvas
 		 * (which perhaps in the glorious future, when track headers
 		 * and the canvas are unified, will actually be true.)
-		 *
-		 * First, translate the event coordinates into the canvas
-		 * coordinate space that DragManager::motion_handler is
-		 * expecting (this requires translation into the *window*
-		 * coordinates for the track canvas window, and then conversion
-		 * from window to canvas coordinate spaces).
-		 * 
-		 * Then fake a DragManager motion event so that when
-		 * maybe_autoscroll asks DragManager for the current pointer
-		 * position it will get the correct answers.
 		*/
 
-		int tx, ty;
-		controls_ebox.translate_coordinates (*_editor.get_track_canvas(), ev->x, ev->y, tx, ty);
+		_editor.maybe_autoscroll (false, true, true);
 
-		/* x-axis of track headers is not shared with the canvas, but
-		   the y-axis is, so we we can get a valid translation here.
-		*/
-
-		Duple canvas_coord = _editor.get_track_canvas()->canvas()->window_to_canvas (Duple (tx, ty));
-		ev->y = (int) floor (canvas_coord.y);
-
-		_editor.drags()->motion_handler ((GdkEvent *) ev, false);
-		_editor.maybe_autoscroll (false, true, false, ev->y_root < _resize_drag_start);
-
-		/* now do the actual TAV resize */
+		/* now schedule the actual TAV resize */
                 int32_t const delta = (int32_t) floor (ev->y_root - _resize_drag_start);
                 _editor.add_to_idle_resize (this, delta);
                 _resize_drag_start = ev->y_root;
diff --git a/libs/canvas/curve.cc b/libs/canvas/curve.cc
index 128aea5462..af7e3c110a 100644
--- a/libs/canvas/curve.cc
+++ b/libs/canvas/curve.cc
@@ -402,7 +402,7 @@ Curve::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 		context->restore ();
 	}
 
-#if 0
+#if 1
 	/* add points */
 	
 	setup_fill_context (context);