4.0.0 (stable):

This is the first stable release describing gtkmm-4.0.

The tarball for 4.0.0 has been created with 'meson dist'.
If you build with Autotools from the tarball, please read the README
file, especially the last paragraph.

* Lots of changes in the example programs due to changes in
  gtk4 and gtkmm4. Most such changes are not listed in this NEWS file.
  (Kjell Ahlstedt)
* Use glibmm-2.68 instead of glibmm-2.64
  Require giomm-2.68 >= 2.68.0 and gtkmm-4.0 >= 4.0.0
  (Kjell Ahlstedt)
* Meson build: Set default value of the 'warnings' option to 'min'
  (Kjell Ahlstedt)
* Describe how the mm-common/skeletonmm project is built with Meson
  (Kjell Ahlstedt)
* input example: Don't include build/config.h
  (Kjell Ahlstedt) Issue #11 (Keyikedalube Ndang)
* Describe how to build a multi-threaded program
  (Kjell Ahlstedt) Issue #12 (Keyikedalube Ndang)
* Remove description of Gtk::Container and Gtk::RadioButton
  Those classes have been removed from gtkmm4
  (Kjell Ahlstedt)
* Meson build: Drop dependence on Perl
  (Kjell Ahlstedt)
* Update the "gtkmm and Win32" appendix
  (Chun-wei Fan) Issue #4 (Daniel Boles)