Add GtkWidgetPath.

GtkWidgetPath represents a widget path. It will mainly used by theming
engines to know detail about the widget hierarchy without actually
accessing the widget.

gtk/gtkwidgetpath.h

@@ -0,0 +1,52 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2010 Carlos Garnacho <carlosg@gnome.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GTK_WIDGET_PATH_H__
+#define __GTK_WIDGET_PATH_H__
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+typedef struct GtkWidgetPath GtkWidgetPath;
+
+typedef gboolean (* GtkWidgetPathForeachFunc) (GType        type,
+                                               const gchar *name,
+                                               gpointer     user_data);
+
+GtkWidgetPath * gtk_widget_path_new (void);
+
+void            gtk_widget_path_prepend_widget_desc (GtkWidgetPath *path,
+                                                     GType          type,
+                                                     const gchar   *name);
+
+GtkWidgetPath * gtk_widget_path_copy                (GtkWidgetPath *path);
+void            gtk_widget_path_free                (GtkWidgetPath *path);
+
+gboolean        gtk_widget_path_has_parent          (GtkWidgetPath *path,
+                                                     GType          type);
+
+void            gtk_widget_path_foreach             (GtkWidgetPath            *path,
+                                                     GtkWidgetPathForeachFunc  func,
+                                                     gpointer                  user_data);
+
+
+G_END_DECLS
+
+#endif /* __GTK_WIDGET_PATH_H__ */