Log Message:
gtkmm3: updated to 3.24.1

3.24.1 (stable):

Gdk:
* RGBA::set_hsv(): Properly interpret hue 360° as red

Documentation:
* Gtk::FileFilter: Several improvements of the documentation
* Gtk::Builder: Don’t use @retval on out args, use @param[out]

Tests:
* Add test of Gdk::RGBA

3.24.0 (stable):

Gdk:
* Deprecate screen_width(), screen_height(),
    screen_width_mm(), screen_height_mm(), flush().
* namespace Gdk::Cairo: Add create_surface_from_pixbuf(),
    get_clip_rectangle(), create_region_from_surface() and draw_from_gl().
* Add FrameClock and FrameTimings
* Window: Add get_frame_clock().
* GLContext: Add unset_use_es().

Gtk:
* CellRendererPixbuf: Fix property_surface()
* AboutDialog: Fix ref count in get_logo()
* MenuItem: add_accel_label(): Make sure accelator keys are shown.
* CssProvider: Deprecate get_default()
  Container: Deprecate focus chains
* Grid: Add default values in attach()
* StyleContext: Add set/get_frame_clock() and property_paint_clock().
    Widget: Add get_frame_clock(), add_tick_callback() and
    remove_tick_callback().
* Image: Add more constructors
* Window: Deprecate get_accel_group() in favour of a new get_accel_groups().
* Range: Deprecate property_[lower|upper]_stepper_sensitivity().
  Settings: Undeprecate property_gtk_cursor_blink(),
    property_gtk_cursor_blink_time(), property_gtk_cursor_blink_timeout(),
    property_gtk_entry_password_hint_timeout().
* AccelGroup: Deprecate signal_accel_activate().
* Add detail_name to some signals:
    AccelGroup: signal_accel_changed().
    AppChooserButton: signal_custom_item_activated().
    LevelBar: signal_offset_changed().
    Widget: signal_child_notify().
* Add make_managed().
* Window: Add show_uri().
* AboutDialog: Add a constructor with a use_header_bar parameter.
* FileChooserDialog: Allow constructing with use-header-bar.
* Add NativeDialog and FileChooserNative.

Demos:
* Update some demo programs.

Build:
* Replace the Visual Studio project files with MSVC NMake project files
* Require giomm-2.4 >= 2.54.0