GdkWindow clean up for offscreen redirection

[Emmanuele Bassi <ebassi gmail com>]

hi all;

the original offscreen redirection patch[1] introduced a clean up work
for GdkWindow[2] in order to implement the offscreen GdkWindow object.

since this affects the various GDK backends, I think it should go
through a round of discussion first.

the offscreen redirection patch needs to implement a GdkOffscreenWindow
class which redirects itself, and every child window, into an offscreen
pixmap. this means that the GdkWindow API should be implementable not
only on a per-backend basis but also by any internal, backend-agnostic
class. in order to achieve that, a GdkWindowImpl interface has been
added, and every GdkWindow<Backend> class must implement it.

this moves all the per-backend public API into GdkWindow, proxying the
GdkWindowImpl vtable functions. the value of this patch, aside from
making it possible to actually implement GdkOffscreenWindow as a
GdkWindow subclass, is also in the clean up itself, which removes a lot
of crud and makes it easier (in my opinion) to implement backends.

I'd like a comment on the patch from the various backends maintainers so
that we can push the clean up forward and have it land in trunk.

ciao,
 Emmanuele.

+++

[1] http://bugzilla.gnome.org/show_bug.cgi?id=318807
[2] the patch has been broken down here:
    http://bugzilla.gnome.org/attachment.cgi?id=104923&action=view
    http://bugzilla.gnome.org/attachment.cgi?id=104924&action=view
    http://bugzilla.gnome.org/attachment.cgi?id=104925&action=view
    http://bugzilla.gnome.org/attachment.cgi?id=104926&action=view
    http://bugzilla.gnome.org/attachment.cgi?id=104927&action=view

    the last attachment is the port of the X11 backend to the new
    GdkWindowImpl interface.

-- 
Emmanuele Bassi,
W: http://www.emmanuelebassi.net
B: http://log.emmanuelebassi.net