CSS API needs enumeration methods

[Peter Hurley <peter hurleysoftware com>]

I'd like to extend the functionality of gtkparasite to show a CSS style
pane for the currently selected widget (ala Firebug).

First, let me clear: this is strictly an interface problem, as all of
the necessary machinery has already been in place for some time.

In fact, currently I have a version of gtkparasite (for Linux only)
which does show the CSS styling (including file, line number and CSS
selectors and statements) by using the debug symbol file to call global
but unexported functions and type-safely walk the necessary internal
library structures (which varies from release to release).

Naturally, it'd be better if this were possible with public methods
instead. Unfortunately, nearly all the CSS APIs lack the necessary
enumeration methods to support this functionality.

For example, it's currently not possible to enumerate the property names
of properties which have been registered via
gtk_style_properties_register_property(). Enumerating registered
property names into a list would be a trivial implementation.

Regards,
Peter Hurley