3.21.3 (unstable):

Gtk:
* AppChooserDialog, FontChooserDialog: Add _UNMANAGEABLE.
  (Kjell Ahlstedt)
* ScrolledWindow: Deprecate remove_with_viewport().
  (Kjell Ahlstedt) Bug #685739
* SizeGroup: Deprecate set/get/property_ignore_hidden().
  (Kjell Ahlstedt)
* Widget: Deprecate send_expose().
  (Kjell Ahlstedt)
* Window: Deprecate begin_paint_rect(), begin_paint_region(),
  end_paint() and create_cairo_context(). Add begin_draw_frame() and
  end_draw_frame() which use the new Gdk::DrawingContext.
  (Kjell Ahlstedt)

Gdk:
* Add DrawingContext.
  (Kjell Ahlstedt)

Build:
* Visual Studio builds: Update gdkmm project
  (Chun-wei Fan)