diff --git a/libgimp/gimpaspectpreview.c b/libgimp/gimpaspectpreview.c
index d16167a8ac..e2fbea012b 100644
--- a/libgimp/gimpaspectpreview.c
+++ b/libgimp/gimpaspectpreview.c
@@ -54,9 +54,7 @@ typedef struct
 } PreviewSettings;
 
 
-static GObject * gimp_aspect_preview_constructor (GType                  type,
-                                                  guint                  n_params,
-                                                  GObjectConstructParam *params);
+static void  gimp_aspect_preview_constructed  (GObject         *object);
 static void  gimp_aspect_preview_dispose      (GObject         *object);
 static void  gimp_aspect_preview_get_property (GObject         *object,
                                                guint            property_id,
@@ -102,7 +100,7 @@ gimp_aspect_preview_class_init (GimpAspectPreviewClass *klass)
   GtkWidgetClass   *widget_class  = GTK_WIDGET_CLASS (klass);
   GimpPreviewClass *preview_class = GIMP_PREVIEW_CLASS (klass);
 
-  object_class->constructor  = gimp_aspect_preview_constructor;
+  object_class->constructed  = gimp_aspect_preview_constructed;
   object_class->dispose      = gimp_aspect_preview_dispose;
   object_class->get_property = gimp_aspect_preview_get_property;
   object_class->set_property = gimp_aspect_preview_set_property;
@@ -134,21 +132,19 @@ gimp_aspect_preview_init (GimpAspectPreview *preview)
                 NULL);
 }
 
-static GObject *
-gimp_aspect_preview_constructor (GType                  type,
-                                 guint                  n_params,
-                                 GObjectConstructParam *params)
+static void
+gimp_aspect_preview_constructed (GObject *object)
 {
-  GObject         *object;
   gchar           *data_name;
   PreviewSettings  settings;
 
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
+
   data_name = g_strdup_printf ("%s-aspect-preview-%d",
                                g_get_prgname (),
                                gimp_aspect_preview_counter++);
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
   if (gimp_get_data (data_name, &settings))
     {
       gimp_preview_set_update (GIMP_PREVIEW (object), settings.update);
@@ -156,8 +152,6 @@ gimp_aspect_preview_constructor (GType                  type,
 
   g_object_set_data_full (object, "gimp-aspect-preview-data-name",
                           data_name, (GDestroyNotify) g_free);
-
-  return object;
 }
 
 static void
diff --git a/libgimp/gimpdrawablepreview.c b/libgimp/gimpdrawablepreview.c
index a472653544..e291dcac9d 100644
--- a/libgimp/gimpdrawablepreview.c
+++ b/libgimp/gimpdrawablepreview.c
@@ -56,9 +56,7 @@ typedef struct
 } PreviewSettings;
 
 
-static GObject * gimp_drawable_preview_constructor (GType                  type,
-                                                    guint                  n_params,
-                                                    GObjectConstructParam *params);
+static void  gimp_drawable_preview_constructed   (GObject         *object);
 static void  gimp_drawable_preview_dispose       (GObject         *object);
 static void  gimp_drawable_preview_get_property  (GObject         *object,
                                                   guint            property_id,
@@ -100,7 +98,7 @@ gimp_drawable_preview_class_init (GimpDrawablePreviewClass *klass)
   GtkWidgetClass   *widget_class  = GTK_WIDGET_CLASS (klass);
   GimpPreviewClass *preview_class = GIMP_PREVIEW_CLASS (klass);
 
-  object_class->constructor  = gimp_drawable_preview_constructor;
+  object_class->constructed  = gimp_drawable_preview_constructed;
   object_class->dispose      = gimp_drawable_preview_dispose;
   object_class->get_property = gimp_drawable_preview_get_property;
   object_class->set_property = gimp_drawable_preview_set_property;
@@ -131,21 +129,19 @@ gimp_drawable_preview_init (GimpDrawablePreview *preview)
                 NULL);
 }
 
-static GObject *
-gimp_drawable_preview_constructor (GType                  type,
-                                   guint                  n_params,
-                                   GObjectConstructParam *params)
+static void
+gimp_drawable_preview_constructed (GObject *object)
 {
-  GObject         *object;
   gchar           *data_name;
   PreviewSettings  settings;
 
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
+
   data_name = g_strdup_printf ("%s-drawable-preview-%d",
                                g_get_prgname (),
                                ++gimp_drawable_preview_counter);
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
   if (gimp_get_data (data_name, &settings))
     {
       gimp_preview_set_update (GIMP_PREVIEW (object), settings.update);
@@ -155,8 +151,6 @@ gimp_drawable_preview_constructor (GType                  type,
 
   g_object_set_data_full (object, "gimp-drawable-preview-data-name",
                           data_name, (GDestroyNotify) g_free);
-
-  return object;
 }
 
 static void
diff --git a/libgimp/gimpzoompreview.c b/libgimp/gimpzoompreview.c
index 458c8beb94..971520ea42 100644
--- a/libgimp/gimpzoompreview.c
+++ b/libgimp/gimpzoompreview.c
@@ -66,9 +66,7 @@ typedef struct
 #define GIMP_ZOOM_PREVIEW_GET_PRIVATE(obj) \
   ((GimpZoomPreviewPrivate *) ((GimpZoomPreview *) (obj))->priv)
 
-static GObject * gimp_zoom_preview_constructor (GType                  type,
-                                                guint                  n_params,
-                                                GObjectConstructParam *params);
+static void     gimp_zoom_preview_constructed     (GObject         *object);
 static void     gimp_zoom_preview_finalize        (GObject         *object);
 static void     gimp_zoom_preview_dispose         (GObject         *object);
 static void     gimp_zoom_preview_get_property    (GObject         *object,
@@ -137,7 +135,7 @@ gimp_zoom_preview_class_init (GimpZoomPreviewClass *klass)
   GtkWidgetClass   *widget_class  = GTK_WIDGET_CLASS (klass);
   GimpPreviewClass *preview_class = GIMP_PREVIEW_CLASS (klass);
 
-  object_class->constructor  = gimp_zoom_preview_constructor;
+  object_class->constructed  = gimp_zoom_preview_constructed;
   object_class->finalize     = gimp_zoom_preview_finalize;
   object_class->dispose      = gimp_zoom_preview_dispose;
   object_class->get_property = gimp_zoom_preview_get_property;
@@ -203,22 +201,20 @@ gimp_zoom_preview_init (GimpZoomPreview *preview)
                                     GTK_POLICY_ALWAYS, GTK_POLICY_ALWAYS);
 }
 
-static GObject *
-gimp_zoom_preview_constructor (GType                  type,
-                               guint                  n_params,
-                               GObjectConstructParam *params)
+static void
+gimp_zoom_preview_constructed (GObject *object)
 {
-  GimpZoomPreviewPrivate *priv;
-  GObject                *object;
+  GimpZoomPreviewPrivate *priv = GIMP_ZOOM_PREVIEW_GET_PRIVATE (object);
   gchar                  *data_name;
   PreviewSettings         settings;
 
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
+
   data_name = g_strdup_printf ("%s-zoom-preview-%d",
                                g_get_prgname (),
                                gimp_zoom_preview_counter++);
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
   if (gimp_get_data (data_name, &settings))
     {
       gimp_preview_set_update (GIMP_PREVIEW (object), settings.update);
@@ -227,8 +223,6 @@ gimp_zoom_preview_constructor (GType                  type,
   g_object_set_data_full (object, "gimp-zoom-preview-data-name",
                           data_name, (GDestroyNotify) g_free);
 
-  priv = GIMP_ZOOM_PREVIEW_GET_PRIVATE (object);
-
   if (! priv->model)
     {
       GimpZoomModel *model = gimp_zoom_model_new ();
@@ -240,8 +234,6 @@ gimp_zoom_preview_constructor (GType                  type,
     }
 
   gimp_zoom_preview_set_adjustments (GIMP_ZOOM_PREVIEW (object), 1.0, 1.0);
-
-  return object;
 }
 
 static void
diff --git a/libgimpwidgets/gimpchainbutton.c b/libgimpwidgets/gimpchainbutton.c
index 4ab76f0284..a16d2dd9ac 100644
--- a/libgimpwidgets/gimpchainbutton.c
+++ b/libgimpwidgets/gimpchainbutton.c
@@ -63,9 +63,7 @@ enum
   LAST_SIGNAL
 };
 
-static GObject * gimp_chain_button_constructor      (GType            type,
-                                                     guint            n_params,
-                                                     GObjectConstructParam *params);
+static void      gimp_chain_button_constructed      (GObject         *object);
 static void      gimp_chain_button_set_property     (GObject         *object,
                                                      guint            property_id,
                                                      const GValue    *value,
@@ -103,7 +101,7 @@ gimp_chain_button_class_init (GimpChainButtonClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
-  object_class->constructor  = gimp_chain_button_constructor;
+  object_class->constructed  = gimp_chain_button_constructed;
   object_class->set_property = gimp_chain_button_set_property;
   object_class->get_property = gimp_chain_button_get_property;
 
@@ -150,17 +148,13 @@ gimp_chain_button_init (GimpChainButton *button)
                     button);
 }
 
-static GObject *
-gimp_chain_button_constructor (GType                  type,
-                               guint                  n_params,
-                               GObjectConstructParam *params)
+static void
+gimp_chain_button_constructed (GObject *object)
 {
-  GObject         *object;
-  GimpChainButton *button;
+  GimpChainButton *button = GIMP_CHAIN_BUTTON (object);
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
-  button = GIMP_CHAIN_BUTTON (object);
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
 
   button->line1 = gimp_chain_line_new (button->position, 1);
   button->line2 = gimp_chain_line_new (button->position, -1);
@@ -191,8 +185,6 @@ gimp_chain_button_constructor (GType                  type,
   gtk_widget_show (button->button);
   gtk_widget_show (button->line1);
   gtk_widget_show (button->line2);
-
-  return object;
 }
 
 static void
diff --git a/libgimpwidgets/gimpcolordisplay.c b/libgimpwidgets/gimpcolordisplay.c
index f6d7d92c51..328618c885 100644
--- a/libgimpwidgets/gimpcolordisplay.c
+++ b/libgimpwidgets/gimpcolordisplay.c
@@ -62,6 +62,7 @@ enum
   LAST_SIGNAL
 };
 
+
 typedef struct
 {
   GimpColorConfig  *config;
@@ -70,9 +71,8 @@ typedef struct
 
 #define GIMP_COLOR_DISPLAY_GET_PRIVATE(obj) (G_TYPE_INSTANCE_GET_PRIVATE ((obj), GIMP_TYPE_COLOR_DISPLAY, GimpColorDisplayPrivate))
 
-static GObject  * gimp_color_display_constructor (GType                  type,
-                                                  guint                  n_params,
-                                                  GObjectConstructParam *params);
+
+static void       gimp_color_display_constructed (GObject       *object);
 static void       gimp_color_display_dispose      (GObject      *object);
 static void       gimp_color_display_set_property (GObject      *object,
                                                    guint         property_id,
@@ -102,7 +102,7 @@ gimp_color_display_class_init (GimpColorDisplayClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
-  object_class->constructor  = gimp_color_display_constructor;
+  object_class->constructed  = gimp_color_display_constructed;
   object_class->dispose      = gimp_color_display_dispose;
   object_class->set_property = gimp_color_display_set_property;
   object_class->get_property = gimp_color_display_get_property;
@@ -154,19 +154,14 @@ gimp_color_display_init (GimpColorDisplay *display)
   display->enabled = FALSE;
 }
 
-static GObject *
-gimp_color_display_constructor (GType                  type,
-                                guint                  n_params,
-                                GObjectConstructParam *params)
+static void
+gimp_color_display_constructed (GObject *object)
 {
-  GObject *object;
-
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
 
   /* emit an initial "changed" signal after all construct properties are set */
   gimp_color_display_changed (GIMP_COLOR_DISPLAY (object));
-
-  return object;
 }
 
 static void
diff --git a/libgimpwidgets/gimpcolorprofilestore.c b/libgimpwidgets/gimpcolorprofilestore.c
index 0e0c043a78..c2212dace1 100644
--- a/libgimpwidgets/gimpcolorprofilestore.c
+++ b/libgimpwidgets/gimpcolorprofilestore.c
@@ -54,9 +54,7 @@ enum
 };
 
 
-static GObject * gimp_color_profile_store_constructor    (GType                  type,
-                                                          guint                  n_params,
-                                                          GObjectConstructParam *params);
+static void      gimp_color_profile_store_constructed    (GObject               *object);
 static void      gimp_color_profile_store_dispose        (GObject               *object);
 static void      gimp_color_profile_store_finalize       (GObject               *object);
 static void      gimp_color_profile_store_set_property   (GObject               *object,
@@ -95,7 +93,7 @@ gimp_color_profile_store_class_init (GimpColorProfileStoreClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
-  object_class->constructor  = gimp_color_profile_store_constructor;
+  object_class->constructed  = gimp_color_profile_store_constructed;
   object_class->dispose      = gimp_color_profile_store_dispose;
   object_class->finalize     = gimp_color_profile_store_finalize;
   object_class->set_property = gimp_color_profile_store_set_property;
@@ -131,18 +129,14 @@ gimp_color_profile_store_init (GimpColorProfileStore *store)
                                    G_N_ELEMENTS (types), types);
 }
 
-static GObject *
-gimp_color_profile_store_constructor  (GType                  type,
-                                       guint                  n_params,
-                                       GObjectConstructParam *params)
+static void
+gimp_color_profile_store_constructed (GObject *object)
 {
-  GObject               *object;
-  GimpColorProfileStore *store;
+  GimpColorProfileStore *store = GIMP_COLOR_PROFILE_STORE (object);
   GtkTreeIter            iter;
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
-  store = GIMP_COLOR_PROFILE_STORE (object);
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
 
   gtk_list_store_append (GTK_LIST_STORE (store), &iter);
   gtk_list_store_set (GTK_LIST_STORE (store), &iter,
@@ -156,8 +150,6 @@ gimp_color_profile_store_constructor  (GType                  type,
     {
       gimp_color_profile_store_load (store, store->history, NULL);
     }
-
-  return object;
 }
 
 static void
diff --git a/libgimpwidgets/gimpdialog.c b/libgimpwidgets/gimpdialog.c
index 9bff8e5a68..5c8e4bd163 100644
--- a/libgimpwidgets/gimpdialog.c
+++ b/libgimpwidgets/gimpdialog.c
@@ -48,27 +48,26 @@ enum
 };
 
 
-static GObject  * gimp_dialog_constructor  (GType            type,
-                                            guint            n_params,
-                                            GObjectConstructParam *params);
-static void       gimp_dialog_dispose      (GObject         *object);
-static void       gimp_dialog_set_property (GObject         *object,
-                                            guint            property_id,
-                                            const GValue    *value,
-                                            GParamSpec      *pspec);
-static void       gimp_dialog_get_property (GObject         *object,
-                                            guint            property_id,
-                                            GValue          *value,
-                                            GParamSpec      *pspec);
+static void       gimp_dialog_constructed  (GObject      *object);
+static void       gimp_dialog_dispose      (GObject      *object);
+static void       gimp_dialog_set_property (GObject      *object,
+                                            guint         property_id,
+                                            const GValue *value,
+                                            GParamSpec   *pspec);
+static void       gimp_dialog_get_property (GObject      *object,
+                                            guint         property_id,
+                                            GValue       *value,
+                                            GParamSpec   *pspec);
 
-static void       gimp_dialog_hide         (GtkWidget       *widget);
-static gboolean   gimp_dialog_delete_event (GtkWidget       *widget,
-                                            GdkEventAny     *event);
-static void       gimp_dialog_close        (GtkDialog       *dialog);
+static void       gimp_dialog_hide         (GtkWidget    *widget);
+static gboolean   gimp_dialog_delete_event (GtkWidget    *widget,
+                                            GdkEventAny  *event);
 
-static void       gimp_dialog_help         (GObject         *dialog);
-static void       gimp_dialog_response     (GtkDialog       *dialog,
-                                            gint             response_id);
+static void       gimp_dialog_close        (GtkDialog    *dialog);
+
+static void       gimp_dialog_help         (GObject      *dialog);
+static void       gimp_dialog_response     (GtkDialog    *dialog,
+                                            gint          response_id);
 
 
 G_DEFINE_TYPE (GimpDialog, gimp_dialog, GTK_TYPE_DIALOG)
@@ -85,7 +84,7 @@ gimp_dialog_class_init (GimpDialogClass *klass)
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
   GtkDialogClass *dialog_class = GTK_DIALOG_CLASS (klass);
 
-  object_class->constructor  = gimp_dialog_constructor;
+  object_class->constructed  = gimp_dialog_constructed;
   object_class->dispose      = gimp_dialog_dispose;
   object_class->set_property = gimp_dialog_set_property;
   object_class->get_property = gimp_dialog_get_property;
@@ -128,16 +127,14 @@ gimp_dialog_init (GimpDialog *dialog)
                     NULL);
 }
 
-static GObject *
-gimp_dialog_constructor (GType                  type,
-                         guint                  n_params,
-                         GObjectConstructParam *params)
+static void
+gimp_dialog_constructed (GObject *object)
 {
-  GObject      *object;
   GimpHelpFunc  help_func;
   const gchar  *help_id;
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
 
   help_func = g_object_get_data (object, "gimp-dialog-help-func");
   help_id   = g_object_get_data (object, "gimp-dialog-help-id");
@@ -162,8 +159,6 @@ gimp_dialog_constructor (GType                  type,
 
       g_object_set_data (object, "gimp-dialog-help-button", button);
     }
-
-  return object;
 }
 
 static void
diff --git a/libgimpwidgets/gimphintbox.c b/libgimpwidgets/gimphintbox.c
index 69e1972cfb..17867758d2 100644
--- a/libgimpwidgets/gimphintbox.c
+++ b/libgimpwidgets/gimphintbox.c
@@ -55,18 +55,18 @@ enum
   PROP_HINT
 };
 
-static GObject * gimp_hint_box_constructor  (GType                  type,
-                                             guint                  n_params,
-                                             GObjectConstructParam *params);
-static void      gimp_hint_box_finalize     (GObject               *object);
-static void      gimp_hint_box_set_property (GObject               *object,
-                                             guint                  property_id,
-                                             const GValue          *value,
-                                             GParamSpec            *pspec);
-static void      gimp_hint_box_get_property (GObject               *object,
-                                             guint                  property_id,
-                                             GValue                *value,
-                                             GParamSpec            *pspec);
+
+static void   gimp_hint_box_constructed  (GObject      *object);
+static void   gimp_hint_box_finalize     (GObject      *object);
+static void   gimp_hint_box_set_property (GObject      *object,
+                                          guint         property_id,
+                                          const GValue *value,
+                                          GParamSpec   *pspec);
+static void   gimp_hint_box_get_property (GObject      *object,
+                                          guint         property_id,
+                                          GValue       *value,
+                                          GParamSpec   *pspec);
+
 
 G_DEFINE_TYPE (GimpHintBox, gimp_hint_box, GTK_TYPE_HBOX)
 
@@ -78,7 +78,7 @@ gimp_hint_box_class_init (GimpHintBoxClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
-  object_class->constructor   = gimp_hint_box_constructor;
+  object_class->constructed   = gimp_hint_box_constructed;
   object_class->finalize      = gimp_hint_box_finalize;
   object_class->set_property  = gimp_hint_box_set_property;
   object_class->get_property  = gimp_hint_box_get_property;
@@ -102,18 +102,14 @@ gimp_hint_box_init (GimpHintBox *box)
   box->hint     = NULL;
 }
 
-static GObject *
-gimp_hint_box_constructor (GType                  type,
-                           guint                  n_params,
-                           GObjectConstructParam *params)
+static void
+gimp_hint_box_constructed (GObject *object)
 {
-  GObject     *object;
-  GimpHintBox *box;
+  GimpHintBox *box = GIMP_HINT_BOX (object);
   GtkWidget   *label;
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
-  box = GIMP_HINT_BOX (object);
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
 
   gtk_box_set_spacing (GTK_BOX (box), 12);
 
@@ -139,8 +135,6 @@ gimp_hint_box_constructor (GType                  type,
                              -1);
   gtk_box_pack_start (GTK_BOX (box), label, FALSE, FALSE, 0);
   gtk_widget_show (label);
-
-  return object;
 }
 
 static void
diff --git a/libgimpwidgets/gimpintstore.c b/libgimpwidgets/gimpintstore.c
index 68ef970366..da7bfa5108 100644
--- a/libgimpwidgets/gimpintstore.c
+++ b/libgimpwidgets/gimpintstore.c
@@ -54,12 +54,9 @@ typedef struct
 } GimpIntStorePrivate;
 
 
-static GObject * gimp_int_store_constructor (GType                  type,
-                                             guint                  n_params,
-                                             GObjectConstructParam *params);
-
 static void  gimp_int_store_tree_model_init (GtkTreeModelIface *iface);
 
+static void  gimp_int_store_constructed     (GObject           *object);
 static void  gimp_int_store_finalize        (GObject           *object);
 static void  gimp_int_store_set_property    (GObject           *object,
                                              guint              property_id,
@@ -93,7 +90,7 @@ gimp_int_store_class_init (GimpIntStoreClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
-  object_class->constructor  = gimp_int_store_constructor;
+  object_class->constructed  = gimp_int_store_constructed;
   object_class->finalize     = gimp_int_store_finalize;
   object_class->set_property = gimp_int_store_set_property;
   object_class->get_property = gimp_int_store_get_property;
@@ -120,26 +117,29 @@ gimp_int_store_class_init (GimpIntStoreClass *klass)
   g_type_class_add_private (object_class, sizeof (GimpIntStorePrivate));
 }
 
+static void
+gimp_int_store_tree_model_init (GtkTreeModelIface *iface)
+{
+  parent_iface = g_type_interface_peek_parent (iface);
+
+  iface->row_inserted = gimp_int_store_row_inserted;
+}
+
 static void
 gimp_int_store_init (GimpIntStore *store)
 {
   store->empty_iter = NULL;
 }
 
-static GObject *
-gimp_int_store_constructor (GType                  type,
-                            guint                  n_params,
-                            GObjectConstructParam *params)
+static void
+gimp_int_store_constructed (GObject *object)
 {
-  GObject             *object;
-  GimpIntStore        *store;
-  GimpIntStorePrivate *priv;
+  GimpIntStore        *store = GIMP_INT_STORE (object);
+  GimpIntStorePrivate *priv  = GIMP_INT_STORE_GET_PRIVATE (store);
   GType                types[GIMP_INT_STORE_NUM_COLUMNS];
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
-  store = GIMP_INT_STORE (object);
-  priv = GIMP_INT_STORE_GET_PRIVATE (store);
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
 
   types[GIMP_INT_STORE_VALUE]     = G_TYPE_INT;
   types[GIMP_INT_STORE_LABEL]     = G_TYPE_STRING;
@@ -152,16 +152,6 @@ gimp_int_store_constructor (GType                  type,
                                    GIMP_INT_STORE_NUM_COLUMNS, types);
 
   gimp_int_store_add_empty (store);
-
-  return object;
-}
-
-static void
-gimp_int_store_tree_model_init (GtkTreeModelIface *iface)
-{
-  parent_iface = g_type_interface_peek_parent (iface);
-
-  iface->row_inserted = gimp_int_store_row_inserted;
 }
 
 static void
diff --git a/libgimpwidgets/gimpstringcombobox.c b/libgimpwidgets/gimpstringcombobox.c
index 847a62d4e2..1895f2a34b 100644
--- a/libgimpwidgets/gimpstringcombobox.c
+++ b/libgimpwidgets/gimpstringcombobox.c
@@ -59,18 +59,15 @@ typedef struct
   ((GimpStringComboBoxPrivate *) ((GimpStringComboBox *) (obj))->priv)
 
 
-static GObject * gimp_string_combo_box_constructor (GType                  type,
-                                                    guint                  n_params,
-                                                    GObjectConstructParam *params);
-
-static void  gimp_string_combo_box_set_property (GObject         *object,
-                                                 guint            property_id,
-                                                 const GValue    *value,
-                                                 GParamSpec      *pspec);
-static void  gimp_string_combo_box_get_property (GObject         *object,
-                                                 guint            property_id,
-                                                 GValue          *value,
-                                                 GParamSpec      *pspec);
+static void   gimp_string_combo_box_constructed  (GObject      *object);
+static void   gimp_string_combo_box_set_property (GObject      *object,
+                                                  guint         property_id,
+                                                  const GValue *value,
+                                                  GParamSpec   *pspec);
+static void   gimp_string_combo_box_get_property (GObject      *object,
+                                                  guint         property_id,
+                                                  GValue       *value,
+                                                  GParamSpec   *pspec);
 
 
 G_DEFINE_TYPE (GimpStringComboBox, gimp_string_combo_box, GTK_TYPE_COMBO_BOX)
@@ -83,7 +80,7 @@ gimp_string_combo_box_class_init (GimpStringComboBoxClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
-  object_class->constructor  = gimp_string_combo_box_constructor;
+  object_class->constructed  = gimp_string_combo_box_constructed;
   object_class->set_property = gimp_string_combo_box_set_property;
   object_class->get_property = gimp_string_combo_box_get_property;
 
@@ -145,18 +142,14 @@ gimp_string_combo_box_init (GimpStringComboBox *combo_box)
                                                  GimpStringComboBoxPrivate);
 }
 
-static GObject *
-gimp_string_combo_box_constructor (GType                  type,
-                                   guint                  n_params,
-                                   GObjectConstructParam *params)
+static void
+gimp_string_combo_box_constructed (GObject *object)
 {
-  GObject                   *object;
-  GimpStringComboBoxPrivate *priv;
+  GimpStringComboBoxPrivate *priv = GIMP_STRING_COMBO_BOX_GET_PRIVATE (object);
   GtkCellRenderer           *cell;
 
-  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);
-
-  priv = GIMP_STRING_COMBO_BOX_GET_PRIVATE (object);
+  if (G_OBJECT_CLASS (parent_class)->constructed)
+    G_OBJECT_CLASS (parent_class)->constructed (object);
 
   priv->text_renderer = cell = gtk_cell_renderer_text_new ();
 
@@ -164,8 +157,6 @@ gimp_string_combo_box_constructor (GType                  type,
   gtk_cell_layout_set_attributes (GTK_CELL_LAYOUT (object), cell,
                                   "text", priv->label_column,
                                   NULL);
-
-  return object;
 }
 
 static void