[gtkmm] LevelBar: Add set_orientation().

[Murray Cumming <murrayc src gnome org>]

commit a985e6125a86336c63aa7889f6d4b40c9d26cd65
Author: Murray Cumming <murrayc murrayc com>
Date:   Mon Sep 14 23:11:36 2015 +0200

    LevelBar: Add set_orientation().
    
    This is just a convenience for until we can break ABI and properly
    derive from Gtk::Orientable.
    Bug #752568 (Tobias Hoffmann)

 gtk/src/levelbar.ccg |    5 +++++
 gtk/src/levelbar.hg  |   15 ++++++++-------
 2 files changed, 13 insertions(+), 7 deletions(-)
---
diff --git a/gtk/src/levelbar.ccg b/gtk/src/levelbar.ccg
index 0d7d964..8e13222 100644
--- a/gtk/src/levelbar.ccg
+++ b/gtk/src/levelbar.ccg
@@ -20,4 +20,9 @@
 namespace Gtk
 {
 
+void LevelBar::set_orientation(Orientation orientation)
+{
+  gtk_orientable_set_orientation(GTK_ORIENTABLE(gobj()), ((GtkOrientation)(orientation)));
+}
+
 } //namespace Gtk
diff --git a/gtk/src/levelbar.hg b/gtk/src/levelbar.hg
index 93a7a18..c655296 100644
--- a/gtk/src/levelbar.hg
+++ b/gtk/src/levelbar.hg
@@ -53,13 +53,6 @@ _WRAP_ENUM(LevelBarMode, GtkLevelBarMode)
  * set the minimum value to 0 and the maximum value to 5 after changing the indicator
  * mode to discrete.
  *
- * gtkmm's LevelBar class should derive from the Orientable interface but that would
- * now require an ABI break. You may instead use the C API to change the orientation.
- * For instance:
- * @code
- * gtk_orientable_set_orientation(GTK_ORIENTABLE(bar.gobj()), GTK_ORIENTATION_VERTICAL);
- * @endcode
- *
  * @ingroup Widgets
  * @newin{3,6}
  */
@@ -71,6 +64,14 @@ public:
   _CTOR_DEFAULT()
   _IGNORE(gtk_level_bar_new)
 
+  //TODO: Remove this when we can break ABI to derive from Orientable.
+  /** Sets the orientation of the widget.
+   *
+   * @newin{3,18}
+   *
+   * @param orientation The widget’s new orientation.
+   */
+  void set_orientation(Orientation orientation);
 
   _WRAP_METHOD(void set_mode(LevelBarMode mode), gtk_level_bar_set_mode)
   _WRAP_METHOD(LevelBarMode get_mode() const, gtk_level_bar_get_mode)