Incompatible Changes from GTK+-1.0 to GTK+-1.2:

* GtkAcceleratorTable has been replaced with GtkAccelGroup

* GtkMenuFactory has been replaced with GtkItemFactory, although
  a version of GtkMenuFactory is provided to ease compatibility.

* GtkButton has been changed to derive from GtkBin. 
 
 To access a button's child, use GTK_BIN (button)->child, instead
 of the old GTK_BUTTON (button)->child.

* The selection API has been slightly modified:

 gtk_selection_add_handler() and gtk_selection_add_handler_full() 
 have been removed. To supply the selection, one now register
 the targets one is interested in with:

  void gtk_selection_add_target (GtkWidget           *widget, 
	  	                 GdkAtom              selection,
			         GdkAtom              target,
			         guint                info);

 or:
  
  void gtk_selection_add_targets (GtkWidget           *widget, 
	  			  GdkAtom              selection,
				  GtkTargetEntry      *targets,
				  guint                ntargets);

 When a request for a selection is received, the new "selection_get"
 signal will be called:

   void  "selection_get"           (GtkWidget          *widget,
				    GtkSelectionData   *selection_data,
				    guint               info,
				    guint               time);

 A "time" parameter has also been added to the "selection_received"
 signal.

  void  "selection_received"       (GtkWidget          *widget,
				    GtkSelectionData   *selection_data,
				    guint               time);

* The old drag and drop API has been completely removed and replaced.
  See the reference documentation for details on the new API.

* Support for Themes has been added. In general, this does
  not affect application code, however, a few new rules should
  be observed:

   - To set a shape for a window, you must use 
     gtk_widget_shape_combine_mask() instead of 
     gdk_window_shape_combine_mask(), or the shape will be
     reset when switching themes.

   - It is no longer permissable to draw directly on an arbitrary
     widget, or to set an arbitrary widget's background pixmap.
     If you need to do that, use a GtkDrawingArea or (for a 
     toplevel) the new GtkDrawWindow widget.

* Scrolled windows do not create an automatic viewport anymore, and
  self scrolling widgets do not provide their own scrollbars any
  further. Self scrolling widgets of the Gtk+ core currently are
  GtkViewport, GtkCList, GtkCTree, GtkText and GtkLayout. All of
  these widgets can be added to a scrolled window as normal children
  with gtk_container_add() and their scrolling abilities will be setup
  appropriatedly in an automatic manner.
  Widgets that do not implement own scrolling abilities but get added
  to a scrolled window in order to have their allocations scrollable
  inside of the scrolled window (e.g. a GtkList) have first to be added
  to a GtkViewport, and then the viewport needs to be added to the
  scrolled window.
  However, the scrolled window code provides a convenience function to
  achive this:
  gtk_scrolled_window_add_with_viewport() which will do exactly what
  it says, add a child widget to a viewport and put that viewport into
  the scrolled window.
  Scrollbar policy adjustment needs to be perfomed on the scrolled window
  with gtk_scrolled_window_set_policy() and is not longer maintained for
  the child widgets (e.g. GtkCList's gtk_clist_set_policy() got removed).