[gtkmm] the canvas

[Paul Davis <paul linuxaudiosystems com>]

i have previously recommended the canvas to many people both on this
(gtkmm) list and on gtk-list. it is theoretically a wonderful widget
that is indispensable when creating more sophisticated GUIs than can
be handled by arrays of widgets statically arranged in a window.

however, i found out from havoc on gtk-list last week that the Gnome2
canvas has been rendered quite buggy by a set of changes made to it
that fundamentally changed the internal implementation of many canvas
item types. in fact, several significant GNOME projects that use the
canvas no longer use GnomeCanvas at all, but a stripped down version
called "foocanvas" that has all the anti-alias (read: client-side
rendering) canvas support ripped out. 

i just want to warn people that the canvas is not what it once was,
nor what it could have been. its a very disappointing development for
me. it appears likely that the ardour project will have to continue
using the GtkCanvas (a backport of GnomeCanvas from Gnome1 to pure
GTK) for the foreseeable future. this is real pain because its not
wrapped by gtkmm at this time, and one of the big wins from moving to
gtkmm2 was going to be adopting a properly C++-wrapped canvas. oh
well. 

--p