libgnomecanvas and libzvt GAIL updates

[Marc Mulcahy <marc mulcahy sun com>]

Hi everyone:

Barring any objections I'll plan to commit initial support for libzvt and 
libgnomecanvas into gail within the next day.  Speak now or forever hold 
your peace-- this will of course add libgnomecanvas and libzvt and all 
their dependencies as new dependencies of gail.  This initial support will 
include the following:


libgnomecanvas

gailcanvas.c gailcanvas.h gailcanvasfactory.c gailcanvasfactory.h:
	This provides access to a single child accessible (the root canvas item 
group).  Most of the accessibility implementation is inherited from GailWidget.

gailcanvasitem.c gailcanvasitem.h:
	This is a class from which accessible implementations for classes deriving 
from GnomeCanvasItem inherit.  It handles returning the proper parent 
accessible.  the logic is that if the item has a parent item, the 
accessible for that item is returned, otherwise, the accessible for the 
canvas containing the item is returned.  GailCanvasItem also implements 
AtkComponent.

gailcanvasgroup.c gailcanvasgroup.h gailcanvasgroupfactory.c 
gailcanvasgroupfactory.h:
	Inherits from GailCanvasItem.  Allows an AT to traverse to the group's 
children items.  This appears to be used only to contain the root group 
items in a canvas.  There is no way through the API for GnomeCanvasGroup to 
add or remove children, and consequently there is no "children_changed" 
signal emitted by GailCanvasGroup.

gailcanvastext.c gailcanvastext.h gailcanvstextfactory.c 
gailcanvastextfactory.h:
	Inherits from GailCanvasItem.  Provides an accessible implementation for 
GnomeCanvasText and GnomeCanvasRichText items.  Currently, screen and 
window coordinate information which is supposed to be made accessible 
through AtkText is not supported due to limitations in libgnomecanvas.  I'm 
exploring possible fixes for this.  Default attribute information is not 
available, and therefore not currently supported.

gailcanvaswidgetfactory.c gailcanvaswidgetfactory.h:
	This factory instantiates the accessible for the widget contained in the 
GnomeCanvasWidget, and reparents it with either the accessible for the 
parent canvas item or the parent canvas.

libzvt

The libzvt support is only partially finished.  The zvt_accessible object 
implements most of AtkText with the glaring omission of attribute 
support.  Selection change notifications which are supported by AtkText can 
not be implemented due to limitations in libzvt.  I have submitted a libzvt 
patch to fix this, and will be submitting a second draft in the next day or so.


Comments on any of this are welcome...

Marc