*** Changes from gtkmm 2.4 to 2.6:

* Added IconView, FileChooserButton, and CellView widgets.

* New API for existing classes:
  TODO

*** Changes from gtkmm 2.0/2.2 to gtkmm 2.4:

* Useless signals not wrapped.

* Use of libsigc++ 2 instead of libsigc++ 1.2. See the glibmm CHANGES for details of the syntax.

* It is now easier to see which signal you should handle, because there are less of them.
  Previously we wrapped key-binding signals, but they were quite useless for gtkmm coders.

* Use of Gdk::Device and Gtk::SelectionData instead of C equivalents
  (Murray Cumming)

* New classes:

  UIManager: Action-based menu and toolbar items. 
    - Add Actions to an ActionGroup.
    - Add the ActionGroup to the UIManager.
    - Layout the Menus and Toolbars, with an XML string. Toolbar items and menu items can share the same Action.
    - Add the Layout string to the UIManager.
    - Get a top-level menu or toolbar from the UIManager and put it in a container.

  ComboBox, ComboBoxText, ComboBoxEntry, CellLayout

  EntryCompletion

  ColorButton, FontButton: Buttons that open selection dialogs when clicked, and show the result inside the button.

  Expander: A disclosure triangle, to hide distracting widgets.

  FileChooser: A new File Selection widget.
    
  RadioToolButton, SeparatorToolItem, ToggleToolButton, ToolItem, ToolButton

  IconTheme, IconInfo
  
* New API for existing classes:
  Gtk::AccelMap: lock_path(), unlock_path()
  Gtk::Alignment: get/set_padding(). Useful for indenting Gtk::Frame contents.
  Gtk::Button: get/set_focus_on_click() get/set_alignment()
  Gtk::ButtonBox: get_child_secondary().
  Gtk::Calendar:
    - display_options() is now set_display_options().
    - New properties.
  Gtk::Clipboard: wait_for_targets(), and a simpler request_targets().
  Gtk::CheckMenuItem: get/set_draw_as_radio()
  Gtk::Entry: get/set_completion()
  Gtk::EventBox: get/set_visible_window(), get/set_above_child()
  Gtk::IconSource: get/set_icon_name()
  Gtk::Menu: attach(), set_monitor()
  Gtk::MenuItem: unset_accel_path()
  Gtk::MenuShell: cancel()
  Gtk::MessageDialog:
    - set_markup()
    - Constructors: Added bool use_markup paramater after message parameter.
      This is an API change, and I'd leak to hear suggestions for alternatives.
  Gtk::TextBuffer: select_range()
  Gtk::TextIter (also known as Gtk::TextBuffer::iterator):
    Added *_visible_* versions of forwards/backwards methods.
  Gtk::TextView:
  - get/set_overwrite(), get/set_accepts_tab()
  - Added WRAP_WORD_CHAR wrap mode.
  Gtk::TreeViewColumn (also known as Gtk::TreeView::Column):
    Added get/set_expand(), get_cell_position()
  Gtk::Widget:
  - queue_resize_no_redraw(), get/set__no_show_all()
  - Added unset_fg(), unset_bg(), unset_font(), unset_text(), unset_base().
  - Added add_modal_grab(), remove_modal_grab(), get_current_modal_grab().
    (Ole Laursen)
  - Added set_window() and set_allocation() for implementing new native widgets.
    (Detlef Reichl)
  Gtk::Window: set_default_icon(), set_keep_above(), set_keep_below()

  Gdk::Cursor: new constructor: Cursor(const Glib::RefPtr<Display>& display, const Glib::RefPtr<Pixbuf>& pixbuf, int x, int y)
  Gdk::Display: flush(), supports_cursor_alpha(), supports_cursor_color(), get_default_cursor_size(),
    get_maximal_cursor_size(), set_double_click_distance(), get_default_group().
  Gdk::Pixbuf: get_formats().
  Gdk::PixbufLoader: create() now has extra bool mime_type parameter.
  Gdk::Window: set_keep_above(), set_keep_below().

  Pango:LayoutLine: get_length(), get_start_index(), and get_layout().