diff --git a/app/widgets/gimptoolpreseteditor.c b/app/widgets/gimptoolpreseteditor.c
index 3f802d12cc..867244c3b7 100644
--- a/app/widgets/gimptoolpreseteditor.c
+++ b/app/widgets/gimptoolpreseteditor.c
@@ -37,6 +37,15 @@
 #include "gimp-intl.h"
 
 
+struct _GimpToolPresetEditorPrivate
+{
+  GimpToolPreset *tool_preset_model;
+
+  GtkWidget      *tool_icon;
+  GtkWidget      *tool_label;
+};
+
+
 /*  local function prototypes  */
 
 static void   gimp_tool_preset_editor_constructed  (GObject              *object);
@@ -73,11 +82,16 @@ gimp_tool_preset_editor_class_init (GimpToolPresetEditorClass *klass)
 
   editor_class->set_data    = gimp_tool_preset_editor_set_data;
   editor_class->title       = _("Tool Preset Editor");
+
+  g_type_class_add_private (klass, sizeof (GimpToolPresetEditorPrivate));
 }
 
 static void
 gimp_tool_preset_editor_init (GimpToolPresetEditor *editor)
 {
+  editor->priv = G_TYPE_INSTANCE_GET_PRIVATE (editor,
+                                              GIMP_TYPE_TOOL_PRESET_EDITOR,
+                                              GimpToolPresetEditorPrivate);
 }
 
 static void
@@ -93,7 +107,7 @@ gimp_tool_preset_editor_constructed (GObject *object)
   if (G_OBJECT_CLASS (parent_class)->constructed)
     G_OBJECT_CLASS (parent_class)->constructed (object);
 
-  preset = editor->tool_preset_model =
+  preset = editor->priv->tool_preset_model =
     g_object_new (GIMP_TYPE_TOOL_PRESET,
                   "gimp", data_editor->context->gimp,
                   NULL);
@@ -106,18 +120,18 @@ gimp_tool_preset_editor_constructed (GObject *object)
   gtk_box_pack_start (GTK_BOX (data_editor), hbox, FALSE, FALSE, 0);
   gtk_widget_show (hbox);
 
-  editor->tool_icon = gtk_image_new ();
-  gtk_box_pack_start (GTK_BOX (hbox), editor->tool_icon,
+  editor->priv->tool_icon = gtk_image_new ();
+  gtk_box_pack_start (GTK_BOX (hbox), editor->priv->tool_icon,
                       FALSE, FALSE, 0);
-  gtk_widget_show (editor->tool_icon);
+  gtk_widget_show (editor->priv->tool_icon);
 
-  editor->tool_label = gtk_label_new ("");
-  gimp_label_set_attributes (GTK_LABEL (editor->tool_label),
+  editor->priv->tool_label = gtk_label_new ("");
+  gimp_label_set_attributes (GTK_LABEL (editor->priv->tool_label),
                              PANGO_ATTR_STYLE, PANGO_STYLE_ITALIC,
                              -1);
-  gtk_box_pack_start (GTK_BOX (hbox), editor->tool_label,
+  gtk_box_pack_start (GTK_BOX (hbox), editor->priv->tool_label,
                       FALSE, FALSE, 0);
-  gtk_widget_show (editor->tool_label);
+  gtk_widget_show (editor->priv->tool_label);
 
   hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
   gtk_box_pack_start (GTK_BOX (data_editor), hbox, FALSE, FALSE, 0);
@@ -176,10 +190,10 @@ gimp_tool_preset_editor_finalize (GObject *object)
 {
   GimpToolPresetEditor *editor = GIMP_TOOL_PRESET_EDITOR (object);
 
-  if (editor->tool_preset_model)
+  if (editor->priv->tool_preset_model)
     {
-      g_object_unref (editor->tool_preset_model);
-      editor->tool_preset_model = NULL;
+      g_object_unref (editor->priv->tool_preset_model);
+      editor->priv->tool_preset_model = NULL;
     }
 
   G_OBJECT_CLASS (parent_class)->finalize (object);
@@ -204,7 +218,7 @@ gimp_tool_preset_editor_set_data (GimpDataEditor *editor,
                         G_CALLBACK (gimp_tool_preset_editor_notify_data),
                         editor);
 
-      if (preset_editor->tool_preset_model)
+      if (preset_editor->priv->tool_preset_model)
         gimp_tool_preset_editor_sync_data (preset_editor);
     }
 }
@@ -240,26 +254,26 @@ gimp_tool_preset_editor_sync_data (GimpToolPresetEditor *editor)
   const gchar    *stock_id;
   gchar          *label;
 
-  g_signal_handlers_block_by_func (editor->tool_preset_model,
+  g_signal_handlers_block_by_func (editor->priv->tool_preset_model,
                                    gimp_tool_preset_editor_notify_model,
                                    editor);
 
   gimp_config_copy (GIMP_CONFIG (data_editor->data),
-                    GIMP_CONFIG (editor->tool_preset_model),
+                    GIMP_CONFIG (editor->priv->tool_preset_model),
                     GIMP_CONFIG_PARAM_SERIALIZE);
 
-  g_signal_handlers_unblock_by_func (editor->tool_preset_model,
+  g_signal_handlers_unblock_by_func (editor->priv->tool_preset_model,
                                      gimp_tool_preset_editor_notify_model,
                                      editor);
 
-  tool_info = editor->tool_preset_model->tool_options->tool_info;
+  tool_info = editor->priv->tool_preset_model->tool_options->tool_info;
 
   stock_id = gimp_viewable_get_stock_id (GIMP_VIEWABLE (tool_info));
   label    = g_strdup_printf (_("%s Preset"), tool_info->blurb);
 
-  gtk_image_set_from_stock (GTK_IMAGE (editor->tool_icon),
+  gtk_image_set_from_stock (GTK_IMAGE (editor->priv->tool_icon),
                             stock_id, GTK_ICON_SIZE_MENU);
-  gtk_label_set_text (GTK_LABEL (editor->tool_label), label);
+  gtk_label_set_text (GTK_LABEL (editor->priv->tool_label), label);
 
   g_free (label);
  }
@@ -277,7 +291,7 @@ gimp_tool_preset_editor_notify_model (GimpToolPreset       *options,
                                        gimp_tool_preset_editor_notify_data,
                                        editor);
 
-      gimp_config_copy (GIMP_CONFIG (editor->tool_preset_model),
+      gimp_config_copy (GIMP_CONFIG (editor->priv->tool_preset_model),
                         GIMP_CONFIG (data_editor->data),
                         GIMP_CONFIG_PARAM_SERIALIZE);
 
@@ -294,15 +308,15 @@ gimp_tool_preset_editor_notify_data (GimpToolPreset       *options,
 {
   GimpDataEditor *data_editor = GIMP_DATA_EDITOR (editor);
 
-  g_signal_handlers_block_by_func (editor->tool_preset_model,
+  g_signal_handlers_block_by_func (editor->priv->tool_preset_model,
                                    gimp_tool_preset_editor_notify_model,
                                    editor);
 
   gimp_config_copy (GIMP_CONFIG (data_editor->data),
-                    GIMP_CONFIG (editor->tool_preset_model),
+                    GIMP_CONFIG (editor->priv->tool_preset_model),
                     GIMP_CONFIG_PARAM_SERIALIZE);
 
-  g_signal_handlers_unblock_by_func (editor->tool_preset_model,
+  g_signal_handlers_unblock_by_func (editor->priv->tool_preset_model,
                                      gimp_tool_preset_editor_notify_model,
                                      editor);
 }
diff --git a/app/widgets/gimptoolpreseteditor.h b/app/widgets/gimptoolpreseteditor.h
index ccd6020824..c88ccbea08 100644
--- a/app/widgets/gimptoolpreseteditor.h
+++ b/app/widgets/gimptoolpreseteditor.h
@@ -30,16 +30,14 @@
 #define GIMP_TOOL_PRESET_EDITOR_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_PRESET_EDITOR, GimpToolPresetEditorClass))
 
 
-typedef struct _GimpToolPresetEditorClass GimpToolPresetEditorClass;
+typedef struct _GimpToolPresetEditorPrivate GimpToolPresetEditorPrivate;
+typedef struct _GimpToolPresetEditorClass   GimpToolPresetEditorClass;
 
 struct _GimpToolPresetEditor
 {
-  GimpDataEditor  parent_instance;
+  GimpDataEditor               parent_instance;
 
-  GimpToolPreset *tool_preset_model;
-
-  GtkWidget      *tool_icon;
-  GtkWidget      *tool_label;
+  GimpToolPresetEditorPrivate *priv;
 };
 
 struct _GimpToolPresetEditorClass