See the file 'INSTALL'
+Release notes for 2.20
+======================
+
+* GtkStatusbar now has a message area (see gtk_status_bar_get_message_area)
+ which makes it easy to place additional widgets inside the statusbar
+ frame or to replace the label widgets. Previously, this was only possible
+ by accessing the innards of the statusbar widget directly. Applications
+ which are doing so may need some adjustments, since the addition of the
+ message area changed the internal widget hierarchy.
+
+* GDK will now set all matching virtual modifiers in the state field of
+ key events. Depending on your X modifier map, this can lead to more bits
+ in the state field being set than before. If you are manually matching
+ key events against key/modifier combinations you should make sure that
+ you properly mask away irrelevant parts of the state field. The
+ gdk_keymap_map_virtual_modifiers() function can help with matching
+ against virtual modifiers.
+
Release notes for 2.18
======================
GDK_NATIVE_WINDOWS makes GDK create a native X11 window for each
GDK window, which might make problematic applications work better.
+* GTK+ calls signal (SIGPIPE, SIG_IGN) during initialization, to ignore
+ SIGPIPE signals, since these are almost never wanted in graphical
+ applications. If you do need to handle SIGPIPE for some reason, reset
+ the handler after gtk_init(), but notice that other libraries (e.g.
+ libdbus or gvfs) might do similar things.
Release notes for 2.16
======================