diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index 1a945651e0..6cfb41aa52 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -1255,12 +1255,12 @@ Editor::set_session (Session *t)
 	if (!_pianoroll) {
 		// XXX this should really not happen here
 		_pianoroll = new Pianoroll ("editor pianoroll");
-		_pianoroll->viewport().set_size_request (600, 120);
+		_pianoroll->viewport().set_size_request (-1, 120);
 	}
 	_pianoroll->set_session (_session);
 
 	_bottom_hbox.pack_start(*_properties_box, true, true);
-	_bottom_hbox.pack_start(_pianoroll->contents(), true, true);
+	/* _pianoroll is packed on demand in Editor::region_selection_changed */
 	_bottom_hbox.show_all();
 
 	if (rhythm_ferret) {
diff --git a/gtk2_ardour/editor_selection.cc b/gtk2_ardour/editor_selection.cc
index 249a64e4bf..5a24bd29ae 100644
--- a/gtk2_ardour/editor_selection.cc
+++ b/gtk2_ardour/editor_selection.cc
@@ -53,6 +53,7 @@
 #include "keyboard.h"
 #include "midi_region_view.h"
 #include "pianoroll.h"
+#include "selection_properties_box.h"
 #include "sfdb_ui.h"
 
 #include "pbd/i18n.h"
@@ -1715,7 +1716,7 @@ Editor::region_selection_changed ()
 	}
 	update_selection_markers ();
 
-	_pianoroll->contents().hide ();
+	bool pack_pianoroll = false;
 	if (selection->regions.size () == 1)  {
 		RegionView* rv = (selection->regions.front ());
 		MidiRegionView* mrv = dynamic_cast<MidiRegionView*> (rv);
@@ -1725,10 +1726,20 @@ Editor::region_selection_changed ()
 			if (mrv && mt && mr) {
 				_pianoroll->set_track (mt);
 				_pianoroll->set_region (mr);
-				_pianoroll->contents().show ();
+				pack_pianoroll = true;
 			}
 		}
 	}
+	Gtkmm2ext::container_clear (_bottom_hbox);
+	if (pack_pianoroll) {
+		_bottom_hbox.pack_start(*_properties_box, false, false);
+		_bottom_hbox.pack_start(_pianoroll->contents(), true, true);
+		_pianoroll->contents().hide ();
+		_pianoroll->contents().show_all ();
+	} else {
+		_bottom_hbox.pack_start(*_properties_box, true, true);
+	}
+	_properties_box->show ();
 }
 
 void
diff --git a/gtk2_ardour/selection_properties_box.cc b/gtk2_ardour/selection_properties_box.cc
index 52ce811af7..c95c04164c 100644
--- a/gtk2_ardour/selection_properties_box.cc
+++ b/gtk2_ardour/selection_properties_box.cc
@@ -180,6 +180,7 @@ SelectionPropertiesBox::selection_changed ()
 
 			_region_fx_box = new RegionFxPropertiesBox (rv->region ());
 			_region_editor_box.pack_start (*_region_fx_box);
+			_region_editor_box.show ();
 			rv->RegionViewGoingAway.connect_same_thread (_region_connection, std::bind (&SelectionPropertiesBox::delete_region_editor, this));
 		}
 		_region_editor_box.show ();