diff --git a/libs/canvas/canvas/item.h b/libs/canvas/canvas/item.h
index dadb38733a..38c3235aa5 100644
--- a/libs/canvas/canvas/item.h
+++ b/libs/canvas/canvas/item.h
@@ -347,6 +347,7 @@ public:
 	void add_child_bounding_boxes (bool include_hidden = false) const;
 	void render_children (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const;
 	void prepare_for_render_children (Rect const & area) const;
+	void size_allocate_children (Rect const & r);
 
 	Duple scroll_offset() const;
   public:
diff --git a/libs/canvas/canvas/root_group.h b/libs/canvas/canvas/root_group.h
index 38ab32db61..da9d9d4061 100644
--- a/libs/canvas/canvas/root_group.h
+++ b/libs/canvas/canvas/root_group.h
@@ -29,7 +29,6 @@ class LIBCANVAS_API Root : public Container
 {
   public:
 	void preferred_size (Duple&, Duple&) const;
-	void size_allocate (Rect const &);
 
   private:
 	friend class Canvas;
diff --git a/libs/canvas/cbox.cc b/libs/canvas/cbox.cc
index 9331a8248b..8f658d43d8 100644
--- a/libs/canvas/cbox.cc
+++ b/libs/canvas/cbox.cc
@@ -509,8 +509,6 @@ cBox::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 
 		if (fill()) {
 
-			cerr << whoami() << " setting fill context with 0x" << std::hex << _fill_color << std::dec << " draw " << draw << endl;
-
 			setup_fill_context (context);
 			context->rectangle (draw.x0, draw.y0, draw.width(), draw.height());
 			context->fill_preserve ();
diff --git a/libs/canvas/item.cc b/libs/canvas/item.cc
index 4610d546ae..29e396d0a8 100644
--- a/libs/canvas/item.cc
+++ b/libs/canvas/item.cc
@@ -24,6 +24,7 @@
 #include "pbd/convert.h"
 
 #include "canvas/canvas.h"
+#include "canvas/constraint_packer.h"
 #include "canvas/debug.h"
 #include "canvas/item.h"
 #include "canvas/scroll_group.h"
@@ -607,6 +608,27 @@ Item::size_allocate (Rect const & r)
 		_position = Duple (r.x0, r.y0);
 		_allocation = r;
 	}
+
+	size_allocate_children (r);
+}
+
+void
+Item::size_allocate_children (Rect const & r)
+{
+	bool have_constraint_container = false;
+
+	for (list<Item*>::const_iterator i = _items.begin(); i != _items.end(); ++i) {
+
+		(*i)->size_allocate (r);
+
+		if (dynamic_cast<ConstraintPacker*> (*i)) {
+			have_constraint_container = true;
+		}
+	}
+
+	if (have_constraint_container) {
+		_bounding_box_dirty = true;
+	}
 }
 
 void
diff --git a/libs/canvas/rectangle.cc b/libs/canvas/rectangle.cc
index 174a2d626a..adcca99252 100644
--- a/libs/canvas/rectangle.cc
+++ b/libs/canvas/rectangle.cc
@@ -288,13 +288,13 @@ Rectangle::vertical_fraction (double y) const
 void
 Rectangle::size_allocate (Rect const & r)
 {
-	_allocation = r;
+	Item::size_allocate (r);
 
 	if (_layout_sensitive) {
-		/* set position, and then set the _rect member with values that
-		   use _position as the origin.
+		/* Item::size_allocate() will have set _position, and then set
+		   the _rect member with values that use _position as the
+		   origin.
 		*/
-		_position = Duple (r.x0, r.y0);
 		Rect r2 (0, 0, r.x1 - r.x0, r.y1 - r.y0);
 		set (r2);
 	}
diff --git a/libs/canvas/root_group.cc b/libs/canvas/root_group.cc
index d32fa0ee5e..5cb2cbd596 100644
--- a/libs/canvas/root_group.cc
+++ b/libs/canvas/root_group.cc
@@ -21,7 +21,6 @@
 
 #include "canvas/root_group.h"
 #include "canvas/canvas.h"
-#include "canvas/constraint_packer.h"
 
 using namespace std;
 using namespace ArdourCanvas;
@@ -48,19 +47,3 @@ Root::preferred_size (Duple& min, Duple& natural) const
 	Item::preferred_size (min, natural);
 }
 
-void
-Root::size_allocate (Rect const & r)
-{
-	bool have_constraint_container = false;
-
-	for (list<Item*>::const_iterator i = _items.begin(); i != _items.end(); ++i) {
-		if (dynamic_cast<ConstraintPacker*> (*i)) {
-			(*i)->size_allocate (r);
-			have_constraint_container = true;
-		}
-	}
-
-	if (have_constraint_container) {
-		_bounding_box_dirty = true;
-	}
-}