* gladeui/glade-xml-utils.h, gladeui/glade-widget-adaptor.[ch], gladeui/glade-widget.[ch]:

Added <add-child-verify-function> semantics to query the plugin if it's ok to add
	  a said "child" to an adaptors widget "parent" and warn the user about it in context.

	* gladeui/glade-project.c: Check glade_widget_add_verify() when pasting widgets

	* gladeui/glade-command.c: Check glade_widget_add_verify() from glade_command_create()

	* gladeui/glade-popup.c: Allow "Add widget here" action to appear for any project object
	  and rely on glade_command_create() to warn the user via glade_widget_add_verify() if
	  adding the widget fails.

	* plugins/gtk+/glade-gtk.c, plugins/gtk+/gtk+.xml.in: Added <add-child-verify-function> support to
	GtkContainer, GtkMenuShell, GtkMenuItem, GtkToolBar, GtkToolItem, GtkToolPalette, GtkToolItemGroup,
	GtkActionGroup, GtkTextTagTable adaptors.

ChangeLog

@@ -1,3 +1,21 @@
+2011-01-28  Tristan Van Berkom <tristanvb@openismus.com>
+
+	* gladeui/glade-xml-utils.h, gladeui/glade-widget-adaptor.[ch], gladeui/glade-widget.[ch]:
+	  Added <add-child-verify-function> semantics to query the plugin if it's ok to add
+	  a said "child" to an adaptors widget "parent" and warn the user about it in context.
+
+	* gladeui/glade-project.c: Check glade_widget_add_verify() when pasting widgets
+
+	* gladeui/glade-command.c: Check glade_widget_add_verify() from glade_command_create()
+
+	* gladeui/glade-popup.c: Allow "Add widget here" action to appear for any project object
+	  and rely on glade_command_create() to warn the user via glade_widget_add_verify() if
+	  adding the widget fails.
+
+	* plugins/gtk+/glade-gtk.c, plugins/gtk+/gtk+.xml.in: Added <add-child-verify-function> support to
+	GtkContainer, GtkMenuShell, GtkMenuItem, GtkToolBar, GtkToolItem, GtkToolPalette, GtkToolItemGroup,
+	GtkActionGroup, GtkTextTagTable adaptors.
+
 2011-01-27  Tristan Van Berkom <tristanvb@openismus.com>
 
 	* plugins/gtk+/gtk+.xml.in, plugins/gtk+/glade-gtk.c: Added support for GtkRecentFilter

gladeui/glade-command.c

@@ -1581,6 +1581,13 @@ glade_command_create (GladeWidgetAdaptor * adaptor, GladeWidget * parent,
       return NULL;
     }
 
+  if (parent && !glade_widget_add_verify (parent, widget, TRUE))
+    {
+      g_object_ref_sink (widget);
+      g_object_unref (widget);
+      return NULL;
+    }
+
   widgets = g_list_prepend (widgets, widget);
   glade_command_push_group (_("Create %s"), glade_widget_get_name (widget));
   glade_command_add (widgets, parent, placeholder, project, FALSE);

gladeui/glade-popup.c

@@ -58,57 +58,23 @@ glade_popup_select_cb (GtkMenuItem * item, GladeWidget * widget)
 			       glade_widget_get_object (widget), TRUE);
 }
 
-static GladePlaceholder *
-find_placeholder (GObject * object)
-{
-  GtkContainer *container;
-  GladePlaceholder *retval = NULL;
-  GtkWidget *child;
-  GList *c, *l;
-
-  if (!GTK_IS_CONTAINER (object))
-    return NULL;
-
-  container = GTK_CONTAINER (object);
-
-  for (c = l = glade_util_container_get_all_children (container);
-       l; l = g_list_next (l))
-    {
-      child = l->data;
-
-      if (GLADE_IS_PLACEHOLDER (child))
-        {
-          retval = GLADE_PLACEHOLDER (child);
-          break;
-        }
-    }
-
-  g_list_free (c);
-
-  return retval;
-}
-
 static void
-glade_popup_placeholder_add_cb (GtkMenuItem * item,
+glade_popup_widget_add_cb (GtkMenuItem * item,
-                                GladePlaceholder * placeholder)
+			   GladeWidget * widget)
 {
-  GladeWidgetAdaptor *adaptor;
-  GladeWidget        *parent;
   GladeProject *project;
+  GladeWidgetAdaptor *adaptor;
 
-
+  project = glade_widget_get_project (widget);
-  parent  = glade_placeholder_get_parent (placeholder);
-  project = glade_placeholder_get_project (placeholder);
   adaptor = glade_project_get_add_item (project);
 
   g_return_if_fail (adaptor != NULL);
 
   if (!glade_util_check_and_warn_scrollable
-      (parent, adaptor, glade_app_get_window ()))
+      (widget, adaptor, glade_app_get_window ()))
     {
-      glade_command_create (adaptor, parent,
+      if (glade_command_create (adaptor, widget,
-                            placeholder,
+				NULL, project))
-                            project);
 
       glade_project_set_add_item (project, NULL);
     }
@@ -423,7 +389,6 @@ glade_popup_create_menu (GladeWidget      *widget,
   GtkWidget          *popup_menu;
   GtkWidget          *separator;
   gboolean            sensitive;
-  GladePlaceholder   *tmp_placeholder;
   GladeWidgetAdaptor *adaptor;
   gchar              *book;
 
@@ -433,21 +398,20 @@ glade_popup_create_menu (GladeWidget      *widget,
 
   if (adaptor)
     {
+      GladeWidget *parent;
       RootAddData *data = g_new (RootAddData, 1);
 
+      parent = placeholder ? glade_placeholder_get_parent (placeholder) : widget;
+
       data->adaptor = adaptor;
       data->project = project;
       g_object_set_data_full (G_OBJECT (popup_menu), "root-data-destroy-me", 
 			      data, (GDestroyNotify)g_free);
 
-      tmp_placeholder = placeholder;
-      if (!tmp_placeholder && widget)
-	tmp_placeholder = find_placeholder (glade_widget_get_object (widget));
-
       glade_popup_append_item (popup_menu, NULL, _("_Add widget here"),
-			       NULL, tmp_placeholder != NULL,
+			       NULL, parent != NULL,
-			       glade_popup_placeholder_add_cb,
+			       glade_popup_widget_add_cb,
-			       tmp_placeholder);
+			       parent);
 
       glade_popup_append_item (popup_menu, NULL, _("Add widget as _toplevel"),
                                NULL, TRUE, glade_popup_root_add_cb, data);

gladeui/glade-project.c

@@ -4619,6 +4619,19 @@ glade_project_command_paste (GladeProject     *project,
       return;
     }
 
+  /* Check that the underlying adaptor allows the paste */
+  if (parent)
+    {
+      for (list = glade_clipboard_widgets (clipboard); list && list->data; list = list->next)
+	{
+	  widget = list->data;
+
+	  if (!glade_widget_add_verify (parent, widget, TRUE))
+	    return;
+	}
+    }
+
+
   /* Check that we have compatible heirarchies */
   for (list = glade_clipboard_widgets (clipboard); list && list->data; list = list->next)
     {
@@ -4637,6 +4650,8 @@ glade_project_command_paste (GladeProject     *project,
 
   /* A GladeWidget that doesnt use placeholders can only paste one
    * at a time
+   *
+   * XXX: Not sure if this has to be true.
    */
   if (GTK_IS_WIDGET (glade_widget_get_object (widget)) &&
       parent && !GWA_USE_PLACEHOLDERS (glade_widget_get_adaptor (parent)) &&

gladeui/glade-widget-adaptor.c

@@ -812,6 +812,20 @@ glade_widget_adaptor_object_construct_object (GladeWidgetAdaptor * adaptor,
   return g_object_newv (adaptor->priv->type, n_parameters, parameters);
 }
 
+static gboolean
+glade_widget_adaptor_object_add_verify (GladeWidgetAdaptor *adaptor,
+					GObject            *parent,
+					GObject            *child,
+					gboolean            user_feedback)
+{
+  if (user_feedback)
+    glade_util_ui_message (glade_app_get_window (),
+			   GLADE_UI_INFO, NULL,
+			   _("%s does not support adding any children."), 
+			   adaptor->priv->title);
+
+  return FALSE;
+}
 
 static void
 glade_widget_adaptor_object_set_property (GladeWidgetAdaptor * adaptor,
@@ -1208,6 +1222,7 @@ glade_widget_adaptor_class_init (GladeWidgetAdaptorClass * adaptor_class)
   adaptor_class->verify_property = NULL;
   adaptor_class->set_property = glade_widget_adaptor_object_set_property;
   adaptor_class->get_property = glade_widget_adaptor_object_get_property;
+  adaptor_class->add_verify = glade_widget_adaptor_object_add_verify;
   adaptor_class->add = NULL;
   adaptor_class->remove = NULL;
   adaptor_class->replace_child = NULL;
@@ -1409,6 +1424,10 @@ gwa_extend_with_node_load_sym (GladeWidgetAdaptorClass * klass,
                                     GLADE_TAG_VERIFY_FUNCTION, &symbol))
     klass->verify_property = symbol;
 
+  if (glade_xml_load_sym_from_node (node, module,
+                                    GLADE_TAG_ADD_CHILD_VERIFY_FUNCTION, &symbol))
+    klass->add_verify = symbol;
+
   if (glade_xml_load_sym_from_node (node, module,
                                     GLADE_TAG_ADD_CHILD_FUNCTION, &symbol))
     klass->add = symbol;
@@ -3063,6 +3082,36 @@ glade_widget_adaptor_verify_property (GladeWidgetAdaptor * adaptor,
   return TRUE;
 }
 
+/**
+ * glade_widget_adaptor_add_verify:
+ * @adaptor:   A #GladeWidgetAdaptor
+ * @parent: A #GObject container
+ * @child: A #GObject child
+ * @user_feedback: whether a notification dialog should be
+ * presented in the case that the child cannot not be added.
+ *
+ * Checks whether @child can be added to @parent.
+ *
+ * If @user_feedback is %TRUE and @child cannot be
+ * added then this shows a notification dialog to the user 
+ * explaining why.
+ *
+ * Returns: whether @child can be added to @parent.
+ */
+gboolean
+glade_widget_adaptor_add_verify (GladeWidgetAdaptor *adaptor,
+				 GObject            *container,
+				 GObject            *child,
+				 gboolean            user_feedback)
+{
+  g_return_val_if_fail (GLADE_IS_WIDGET_ADAPTOR (adaptor), FALSE);
+  g_return_val_if_fail (G_IS_OBJECT (container), FALSE);
+  g_return_val_if_fail (G_IS_OBJECT (child), FALSE);
+  g_return_val_if_fail (g_type_is_a (G_OBJECT_TYPE (container), adaptor->priv->type), FALSE);
+
+  return GLADE_WIDGET_ADAPTOR_GET_CLASS (adaptor)->add_verify (adaptor, container, child, user_feedback);
+}
+
 /**
  * glade_widget_adaptor_add:
  * @adaptor:   A #GladeWidgetAdaptor

gladeui/glade-widget-adaptor.h

@@ -295,9 +295,30 @@ typedef gboolean (* GladeChildVerifyPropertyFunc) (GladeWidgetAdaptor *adaptor,
 						   const gchar        *property_name,
 						   const GValue       *value);
 
+/**
+ * GladeAddChildVerifyFunc:
+ * @adaptor: A #GladeWidgetAdaptor
+ * @parent: A #GObject container
+ * @child: A #GObject child
+ * @user_feedback: whether a notification dialog should be
+ * presented in the case that the child cannot not be added.
+ *
+ * Checks whether @child can be added to @parent.
+ *
+ * If @user_feedback is %TRUE and @child cannot be
+ * added then this shows a notification dialog to the user 
+ * explaining why.
+ *
+ * Returns: whether @child can be added to @parent.
+ */
+typedef gboolean (* GladeAddChildVerifyFunc)      (GladeWidgetAdaptor *adaptor,
+						   GObject            *parent,
+						   GObject            *child,
+						   gboolean            user_feedback);
 
 /**
  * GladeGetChildrenFunc:
+ * @adaptor: A #GladeWidgetAdaptor
  * @container: A #GObject container
  *
  * A function called to get @containers children.
@@ -309,6 +330,7 @@ typedef GList   *(* GladeGetChildrenFunc)         (GladeWidgetAdaptor *adaptor,
 
 /**
  * GladeAddChildFunc:
+ * @adaptor: A #GladeWidgetAdaptor
  * @parent: A #GObject container
  * @child: A #GObject child
  *
@@ -317,8 +339,10 @@ typedef GList   *(* GladeGetChildrenFunc)         (GladeWidgetAdaptor *adaptor,
 typedef void     (* GladeAddChildFunc)            (GladeWidgetAdaptor *adaptor,
 						   GObject            *parent,
 						   GObject            *child);
+
 /**
  * GladeRemoveChildFunc:
+ * @adaptor: A #GladeWidgetAdaptor
  * @parent: A #GObject container
  * @child: A #GObject child
  *
@@ -330,6 +354,7 @@ typedef void     (* GladeRemoveChildFunc)         (GladeWidgetAdaptor *adaptor,
 
 /**
  * GladeReplaceChildFunc:
+ * @adaptor: A #GladeWidgetAdaptor
  * @container: A #GObject container
  * @old_obj: The old #GObject child
  * @new_obj: The new #GObject child to take its place
@@ -364,6 +389,7 @@ typedef GObject *(* GladeConstructObjectFunc)     (GladeWidgetAdaptor *adaptor,
 
 /**
  * GladePostCreateFunc:
+ * @adaptor: A #GladeWidgetAdaptor
  * @object: a #GObject
  * @reason: a #GladeCreateReason
  *
@@ -376,6 +402,7 @@ typedef void     (* GladePostCreateFunc)          (GladeWidgetAdaptor *adaptor,
 
 /**
  * GladeGetInternalFunc:
+ * @adaptor: A #GladeWidgetAdaptor
  * @parent: A #GObject composite object
  * @name: A string identifier
  *
@@ -601,6 +628,7 @@ struct _GladeWidgetAdaptorClass
    */
   GladeGetPropertyFunc get_property;
 
+  GladeAddChildVerifyFunc    add_verify;       /* Checks if a child can be added */
   GladeAddChildFunc          add;              /* Adds a new child of this type */
   GladeRemoveChildFunc       remove;           /* Removes a child from the container */
   GladeGetChildrenFunc       get_children;     /* Returns a list of direct children for
@@ -713,6 +741,10 @@ gboolean              glade_widget_adaptor_verify_property    (GladeWidgetAdapto
 							       GObject            *object,
 							       const gchar        *property_name,
 							       const GValue       *value);
+gboolean              glade_widget_adaptor_add_verify         (GladeWidgetAdaptor *adaptor,
+							       GObject            *container,
+							       GObject            *child,
+							       gboolean            user_feedback);
 void                  glade_widget_adaptor_add                (GladeWidgetAdaptor *adaptor,
 							       GObject            *container,
 							       GObject            *child);

gladeui/glade-widget.c

@@ -2304,6 +2304,36 @@ glade_widget_copy_properties (GladeWidget * widget,
     }
 }
 
+
+/**
+ * glade_widget_add_verify:
+ * @widget: A #GladeWidget
+ * @child: The child #GladeWidget to add
+ * @user_feedback: whether a notification dialog should be
+ * presented in the case that the child cannot not be added.
+ *
+ * Checks whether @child can be added to @parent.
+ *
+ * If @user_feedback is %TRUE and @child cannot be
+ * added then this shows a notification dialog to the user 
+ * explaining why.
+ *
+ * Returns: whether @child can be added to @widget.
+ */
+gboolean
+glade_widget_add_verify (GladeWidget      *widget,
+			 GladeWidget      *child,
+			 gboolean          user_feedback)
+{
+  g_return_val_if_fail (GLADE_IS_WIDGET (widget), FALSE);
+  g_return_val_if_fail (GLADE_IS_WIDGET (child), FALSE);
+
+  return glade_widget_adaptor_add_verify (widget->priv->adaptor,
+					  widget->priv->object,
+					  child->priv->object,
+					  user_feedback);
+}
+
 /**
  * glade_widget_add_child:
  * @parent: A #GladeWidget

gladeui/glade-widget.h

@@ -69,6 +69,10 @@ GType                   glade_widget_get_type		    (void);
 
 GladeWidget            *glade_widget_get_from_gobject       (gpointer          object);
 
+gboolean                glade_widget_add_verify             (GladeWidget      *parent,
+							     GladeWidget      *child,
+							     gboolean          user_feedback);
+
 void                    glade_widget_add_child              (GladeWidget      *parent,
 							     GladeWidget      *child,
 							     gboolean          at_mouse);

gladeui/glade-xml-utils.h

@@ -93,6 +93,7 @@ typedef struct _GladeProject        GladeProject;
 #define GLADE_TAG_POST_CREATE_FUNCTION            "post-create-function"
 #define GLADE_TAG_GET_INTERNAL_CHILD_FUNCTION     "get-internal-child-function"
 #define GLADE_TAG_ADD_CHILD_FUNCTION              "add-child-function"
+#define GLADE_TAG_ADD_CHILD_VERIFY_FUNCTION       "add-child-verify-function"
 #define GLADE_TAG_REMOVE_CHILD_FUNCTION           "remove-child-function"
 #define GLADE_TAG_GET_CHILDREN_FUNCTION           "get-children-function"
 #define GLADE_TAG_CHILD_SET_PROP_FUNCTION         "child-set-property-function"

plugins/gtk+/glade-gtk.c

@@ -1071,6 +1071,50 @@ glade_gtk_container_post_create (GladeWidgetAdaptor * adaptor,
     }
 }
 
+gboolean
+glade_gtk_container_add_verify (GladeWidgetAdaptor *adaptor,
+				GtkWidget          *container,
+				GtkWidget          *child,
+				gboolean            user_feedback)
+{
+  GladeWidget *gwidget = glade_widget_get_from_gobject (container);
+
+  if (GTK_IS_WINDOW (child))
+    {
+      if (user_feedback)
+	glade_util_ui_message (glade_app_get_window (),
+			       GLADE_UI_INFO, NULL,
+			       _("Cannot add a toplevel window to a containter."));
+
+      return FALSE;
+    }
+  else if (!GTK_IS_WIDGET (child) ||
+	   GTK_IS_TOOL_ITEM (child) ||
+	   GTK_IS_MENU_ITEM (child))
+    {
+      if (user_feedback)
+	glade_util_ui_message (glade_app_get_window (),
+			       GLADE_UI_INFO, NULL,
+			       _("Only widgets can be added to a %s."),
+			       glade_widget_adaptor_get_title (adaptor));
+
+      return FALSE;
+    }
+  else if (GWA_USE_PLACEHOLDERS (adaptor) &&
+	   glade_util_count_placeholders (gwidget) == 0)
+    {
+      if (user_feedback)
+	glade_util_ui_message (glade_app_get_window (),
+			       GLADE_UI_INFO, NULL,
+			       _("This %s has no placeholders available to add children."),
+			       glade_widget_adaptor_get_title (adaptor));
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_container_replace_child (GladeWidgetAdaptor * adaptor,
                                    GtkWidget * container,
@@ -6045,6 +6089,32 @@ glade_gtk_menu_constructor (GType type,
 }
 
 /* ----------------------------- GtkMenuShell ------------------------------ */
+gboolean
+glade_gtk_menu_shell_add_verify (GladeWidgetAdaptor *adaptor,
+				 GtkWidget          *container,
+				 GtkWidget          *child,
+				 gboolean            user_feedback)
+{
+  if (!GTK_IS_MENU_ITEM (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *menu_item_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_MENU_ITEM);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (menu_item_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_menu_shell_add_child (GladeWidgetAdaptor * adaptor,
                                 GObject * object, GObject * child)
@@ -6645,6 +6715,44 @@ glade_gtk_menu_item_get_children (GladeWidgetAdaptor * adaptor,
   return list;
 }
 
+gboolean
+glade_gtk_menu_item_add_verify (GladeWidgetAdaptor *adaptor,
+				GtkWidget          *container,
+				GtkWidget          *child,
+				gboolean            user_feedback)
+{
+  if (!GTK_IS_MENU (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *menu_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_MENU);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (menu_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+  else if (GTK_IS_SEPARATOR_MENU_ITEM (container))
+    {
+      if (user_feedback)
+	{
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("A %s cannot have any children."),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_menu_item_add_child (GladeWidgetAdaptor * adaptor,
                                GObject * object, GObject * child)
@@ -6724,48 +6832,6 @@ glade_gtk_menu_item_set_property (GladeWidgetAdaptor * adaptor,
 }
 
 /* ----------------------------- GtkImageMenuItem ------------------------------ */
-
-GList *
-glade_gtk_image_menu_item_get_children (GladeWidgetAdaptor * adaptor,
-                                        GObject * object)
-{
-  GList *list = NULL;
-  GtkWidget *child;
-  GladeWidget *gitem;
-
-  gitem = glade_widget_get_from_gobject (object);
-
-  if ((child = gtk_menu_item_get_submenu (GTK_MENU_ITEM (object))))
-    list = g_list_append (list, child);
-
-  return list;
-}
-
-void
-glade_gtk_image_menu_item_add_child (GladeWidgetAdaptor * adaptor,
-                                     GObject * object, GObject * child)
-{
-  g_return_if_fail (GTK_IS_MENU_ITEM (object));
-
-  if (GTK_IS_IMAGE (child))
-    gtk_image_menu_item_set_image (GTK_IMAGE_MENU_ITEM (object),
-                                   GTK_WIDGET (child));
-  else
-    GWA_GET_CLASS (GTK_TYPE_MENU_ITEM)->add (adaptor, object, child);
-}
-
-void
-glade_gtk_image_menu_item_remove_child (GladeWidgetAdaptor * adaptor,
-                                        GObject * object, GObject * child)
-{
-  g_return_if_fail (GTK_IS_MENU_ITEM (object));
-
-  if (GTK_IS_IMAGE (child))
-    gtk_image_menu_item_set_image (GTK_IMAGE_MENU_ITEM (object), NULL);
-  else
-    GWA_GET_CLASS (GTK_TYPE_MENU_ITEM)->remove (adaptor, object, child);
-}
-
 static void
 glade_gtk_image_menu_item_set_use_stock (GObject * object, const GValue * value)
 {
@@ -7248,6 +7314,32 @@ glade_gtk_toolbar_set_child_property (GladeWidgetAdaptor * adaptor,
                                                   property_name, value);
 }
 
+gboolean
+glade_gtk_toolbar_add_verify (GladeWidgetAdaptor *adaptor,
+			      GtkWidget          *container,
+			      GtkWidget          *child,
+			      gboolean            user_feedback)
+{
+  if (!GTK_IS_TOOL_ITEM (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *tool_item_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_TOOL_ITEM);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (tool_item_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_toolbar_add_child (GladeWidgetAdaptor * adaptor,
                              GObject * object, GObject * child)
@@ -7416,6 +7508,32 @@ glade_gtk_tool_palette_set_child_property (GladeWidgetAdaptor * adaptor,
                                                   property_name, value);
 }
 
+gboolean
+glade_gtk_tool_palette_add_verify (GladeWidgetAdaptor *adaptor,
+				   GtkWidget          *container,
+				   GtkWidget          *child,
+				   gboolean            user_feedback)
+{
+  if (!GTK_IS_TOOL_ITEM_GROUP (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *tool_item_group_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_TOOL_ITEM_GROUP);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (tool_item_group_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_tool_palette_add_child (GladeWidgetAdaptor * adaptor,
 				  GObject * object, GObject * child)
@@ -7521,6 +7639,32 @@ glade_gtk_tool_palette_action_activate (GladeWidgetAdaptor * adaptor,
 }
 
 /* ----------------------------- GtkToolItemGroup ------------------------------ */
+gboolean
+glade_gtk_tool_item_group_add_verify (GladeWidgetAdaptor *adaptor,
+				      GtkWidget          *container,
+				      GtkWidget          *child,
+				      gboolean            user_feedback)
+{
+  if (!GTK_IS_TOOL_ITEM (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *tool_item_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_TOOL_ITEM);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (tool_item_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_tool_item_group_add_child (GladeWidgetAdaptor * adaptor,
 				     GObject * object, GObject * child)
@@ -7890,6 +8034,32 @@ glade_gtk_menu_tool_button_get_children (GladeWidgetAdaptor * adaptor,
   return list;
 }
 
+gboolean
+glade_gtk_menu_tool_button_add_verify (GladeWidgetAdaptor *adaptor,
+				       GtkWidget          *container,
+				       GtkWidget          *child,
+				       gboolean            user_feedback)
+{
+  if (!GTK_IS_MENU (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *menu_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_MENU);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (menu_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_menu_tool_button_add_child (GladeWidgetAdaptor * adaptor,
                                       GObject * object, GObject * child)
@@ -7901,8 +8071,6 @@ glade_gtk_menu_tool_button_add_child (GladeWidgetAdaptor * adaptor,
       gtk_menu_tool_button_set_menu (GTK_MENU_TOOL_BUTTON (object),
 				     GTK_WIDGET (child));
     }
-  else
-    GWA_GET_CLASS (GTK_TYPE_TOOL_BUTTON)->add (adaptor, object, child);
 }
 
 void
@@ -7915,8 +8083,6 @@ glade_gtk_menu_tool_button_remove_child (GladeWidgetAdaptor * adaptor,
 
       g_object_set_data (child, "special-child-type", NULL);
     }
-  else
-    GWA_GET_CLASS (GTK_TYPE_TOOL_BUTTON)->remove (adaptor, object, child);
 }
 
 void
@@ -10939,6 +11105,32 @@ glade_gtk_cell_renderer_read_widget (GladeWidgetAdaptor * adaptor,
 }
 
 /*--------------------------- GtkCellLayout ---------------------------------*/
+gboolean
+glade_gtk_cell_layout_add_verify (GladeWidgetAdaptor *adaptor,
+				  GtkWidget          *container,
+				  GtkWidget          *child,
+				  gboolean            user_feedback)
+{
+  if (!GTK_IS_CELL_RENDERER (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *cell_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_CELL_RENDERER);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (cell_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_cell_layout_add_child (GladeWidgetAdaptor * adaptor,
                                  GObject * container, GObject * child)
@@ -11659,6 +11851,32 @@ glade_gtk_action_post_create (GladeWidgetAdaptor * adaptor,
 }
 
 /*--------------------------- GtkActionGroup ---------------------------------*/
+gboolean
+glade_gtk_action_group_add_verify (GladeWidgetAdaptor *adaptor,
+				   GtkWidget          *container,
+				   GtkWidget          *child,
+				   gboolean            user_feedback)
+{
+  if (!GTK_IS_ACTION (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *action_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_ACTION);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (action_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_action_group_add_child (GladeWidgetAdaptor * adaptor,
                                   GObject * container, GObject * child)
@@ -11837,6 +12055,32 @@ glade_gtk_action_action_activate (GladeWidgetAdaptor *adaptor,
 
 
 /*--------------------------- GtkTextTagTable ---------------------------------*/
+gboolean
+glade_gtk_text_tag_table_add_verify (GladeWidgetAdaptor *adaptor,
+				     GtkWidget          *container,
+				     GtkWidget          *child,
+				     gboolean            user_feedback)
+{
+  if (!GTK_IS_TEXT_TAG (child))
+    {
+      if (user_feedback)
+	{
+	  GladeWidgetAdaptor *tag_adaptor = 
+	    glade_widget_adaptor_get_by_type (GTK_TYPE_TEXT_TAG);
+
+	  glade_util_ui_message (glade_app_get_window (),
+				 GLADE_UI_INFO, NULL,
+				 _("Only a %s can be added to a %s."),
+				 glade_widget_adaptor_get_title (tag_adaptor),
+				 glade_widget_adaptor_get_title (adaptor));
+	}
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 void
 glade_gtk_text_tag_table_add_child (GladeWidgetAdaptor * adaptor,
 				    GObject * container, GObject * child)

plugins/gtk+/gtk+.xml.in

@@ -281,7 +281,7 @@ embedded in another object</_tooltip>
 
     <glade-widget-class name="GtkContainer" _title="Container" use-placeholders="True">
       <post-create-function>glade_gtk_container_post_create</post-create-function>
-
+      <add-child-verify-function>glade_gtk_container_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_container_add_child</add-child-function>
       <remove-child-function>glade_gtk_container_remove_child</remove-child-function> 
       <replace-child-function>glade_gtk_container_replace_child</replace-child-function>
@@ -443,6 +443,7 @@ embedded in another object</_tooltip>
 
     <glade-widget-class name="GtkMenuShell" _title="Menu Shell" use-placeholders="False" since="2.16">
       <post-create-function>empty</post-create-function>
+      <add-child-verify-function>glade_gtk_menu_shell_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_menu_shell_add_child</add-child-function>
       <remove-child-function>glade_gtk_menu_shell_remove_child</remove-child-function>
       <child-set-property-function>glade_gtk_menu_shell_set_child_property</child-set-property-function>
@@ -470,6 +471,7 @@ embedded in another object</_tooltip>
       <post-create-function>glade_gtk_menu_item_post_create</post-create-function>
       <get-children-function>glade_gtk_menu_item_get_children</get-children-function>
       <set-property-function>glade_gtk_menu_item_set_property</set-property-function>
+      <add-child-verify-function>glade_gtk_menu_item_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_menu_item_add_child</add-child-function>
       <remove-child-function>glade_gtk_menu_item_remove_child</remove-child-function>
       <action-activate-function>glade_gtk_menu_item_action_activate</action-activate-function>
@@ -507,9 +509,6 @@ embedded in another object</_tooltip>
       <read-widget-function>glade_gtk_image_menu_item_read_widget</read-widget-function>
       <write-widget-function>glade_gtk_image_menu_item_write_widget</write-widget-function>
       <set-property-function>glade_gtk_image_menu_item_set_property</set-property-function>
-      <get-children-function>glade_gtk_image_menu_item_get_children</get-children-function>
-      <add-child-function>glade_gtk_image_menu_item_add_child</add-child-function>
-      <remove-child-function>glade_gtk_image_menu_item_remove_child</remove-child-function>
       <create-editable-function>glade_gtk_image_menu_item_create_editable</create-editable-function>
       <properties>
         <property id="use-stock" default="True" visible="False" save-always="True" since="2.16"/>
@@ -569,6 +568,7 @@ embedded in another object</_tooltip>
       
     <glade-widget-class name="GtkToolbar" generic-name="toolbar" _title="Tool Bar" use-placeholders="False">
       <post-create-function>glade_gtk_toolbar_post_create</post-create-function>
+      <add-child-verify-function>glade_gtk_toolbar_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_toolbar_add_child</add-child-function>
       <remove-child-function>glade_gtk_toolbar_remove_child</remove-child-function>
       <child-set-property-function>glade_gtk_toolbar_set_child_property</child-set-property-function>
@@ -619,6 +619,7 @@ embedded in another object</_tooltip>
     <glade-widget-class name="GtkToolPalette" generic-name="toolpalette" _title="Tool Palette" 
 			use-placeholders="False" since="2.20">
       <post-create-function>glade_gtk_toolbar_post_create</post-create-function>
+      <add-child-verify-function>glade_gtk_tool_palette_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_tool_palette_add_child</add-child-function>
       <remove-child-function>glade_gtk_tool_palette_remove_child</remove-child-function>
       <child-set-property-function>glade_gtk_tool_palette_set_child_property</child-set-property-function>
@@ -661,6 +662,7 @@ embedded in another object</_tooltip>
 			use-placeholders="False" since="2.20">
       <post-create-function>empty</post-create-function>
       <set-property-function>glade_gtk_tool_item_group_set_property</set-property-function>
+      <add-child-verify-function>glade_gtk_tool_item_group_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_tool_item_group_add_child</add-child-function>
       <remove-child-function>glade_gtk_tool_item_group_remove_child</remove-child-function>
       <create-editable-function>glade_gtk_tool_item_group_create_editable</create-editable-function>
@@ -754,6 +756,7 @@ embedded in another object</_tooltip>
     
     <glade-widget-class name="GtkMenuToolButton" generic-name="menutoolbutton" use-placeholders="False"
 			_title="Menu Tool Button">
+      <add-child-verify-function>glade_gtk_menu_tool_button_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_menu_tool_button_add_child</add-child-function>
       <remove-child-function>glade_gtk_menu_tool_button_remove_child</remove-child-function>
       <replace-child-function>glade_gtk_menu_tool_button_replace_child</replace-child-function>
@@ -1155,6 +1158,7 @@ embedded in another object</_tooltip>
     <glade-widget-class name="GtkComboBox" generic-name="combobox" _title="Combo Box">
       <post-create-function>glade_gtk_combo_box_post_create</post-create-function>
       <set-property-function>glade_gtk_combo_box_set_property</set-property-function>
+      <add-child-verify-function>glade_gtk_cell_layout_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_cell_layout_add_child</add-child-function>
       <remove-child-function>glade_gtk_cell_layout_remove_child</remove-child-function> 
       <get-children-function>glade_gtk_combo_box_get_children</get-children-function>
@@ -1925,6 +1929,7 @@ embedded in another object</_tooltip>
 
     <glade-widget-class name="GtkActionGroup" generic-name="actiongroup" _title="Action Group" 
 			toplevel="True" use-placeholders="False">
+      <add-child-verify-function>glade_gtk_action_group_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_action_group_add_child</add-child-function>
       <remove-child-function>glade_gtk_action_group_remove_child</remove-child-function>
       <get-children-function>glade_gtk_action_group_get_children</get-children-function>
@@ -2060,6 +2065,7 @@ embedded in another object</_tooltip>
     </glade-widget-class>
 
     <glade-widget-class name="GtkTreeViewColumn" generic-name="treeviewcolumn" _title="Tree View Column">
+      <add-child-verify-function>glade_gtk_cell_layout_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_cell_layout_add_child</add-child-function>
       <remove-child-function>glade_gtk_cell_layout_remove_child</remove-child-function> 
       <get-children-function>glade_gtk_cell_layout_get_children</get-children-function>
@@ -2102,6 +2108,7 @@ embedded in another object</_tooltip>
 
     <glade-widget-class name="GtkIconView" generic-name="iconview" _title="Icon View">
       <post-create-function>empty</post-create-function>
+      <add-child-verify-function>glade_gtk_cell_layout_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_cell_layout_add_child</add-child-function>
       <remove-child-function>glade_gtk_cell_layout_remove_child</remove-child-function> 
       <get-children-function>glade_gtk_cell_layout_get_children</get-children-function>
@@ -3355,6 +3362,7 @@ embedded in another object</_tooltip>
 
     <glade-widget-class name="GtkTextTagTable" generic-name="texttagtable" _title="Text Tag Table" 
 			toplevel="True">
+      <add-child-verify-function>glade_gtk_text_tag_table_add_verify</add-child-verify-function>
       <add-child-function>glade_gtk_text_tag_table_add_child</add-child-function>
       <remove-child-function>glade_gtk_text_tag_table_remove_child</remove-child-function> 
       <get-children-function>glade_gtk_text_tag_table_get_children</get-children-function>