[gtkmm] Gdk::Window: begin_draw_frame(): Add (optional) context.

[Murray Cumming <murrayc src gnome org>]

commit d7f60bdb9890b701d6c630f9ab79116b43b70261
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Dec 7 11:08:09 2016 +0100

    Gdk::Window: begin_draw_frame(): Add (optional) context.

 gdk/src/window.hg |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gdk/src/window.hg b/gdk/src/window.hg
index 0e425f0..a0daabb 100644
--- a/gdk/src/window.hg
+++ b/gdk/src/window.hg
@@ -364,7 +364,7 @@ public:
    */
   _WRAP_METHOD(Glib::RefPtr<Gdk::GLContext> create_gl_context(), gdk_window_create_gl_context, errthrow)
 
-  _WRAP_METHOD(Glib::RefPtr<DrawingContext> begin_draw_frame(const ::Cairo::RefPtr<const ::Cairo::Region>& 
region), gdk_window_begin_draw_frame, refreturn)
+  _WRAP_METHOD(Glib::RefPtr<DrawingContext> begin_draw_frame(const Glib::RefPtr<DrawingContext>& context{?}, 
const ::Cairo::RefPtr<const ::Cairo::Region>& region) gdk_window_begin_draw_frame, refreturn)
   _WRAP_METHOD(void end_draw_frame(const Glib::RefPtr<DrawingContext>& context), gdk_window_end_draw_frame)
 
   _IGNORE_SIGNAL("moved-to-rect")dnl// Private