How to override theming background image?

[Bogdan Gheorghe <gheorghe ca ibm com>]

Hi -

GtkWidget provides API to override the
background color defined in the Gtk Theme (
gtk_widget_override_background_color
). 

It doesn't seem to provide anything
similar to override the background image other than building a CSS stylesheet
and using a GtkCssProvider to load it. 

Using this approach requires that the
image resides somewhere in the filesystem . If you have an image already
in memory you can't use it without first saving it out.

Another approach would be to write a
custom GtkStyleProvider (similar to the GtkModifierStyle) which provides
an override background image function. This approach seems impossible as
a portion of the style provider implementation is private (the GtkStyleProviderPrivate
interface).

Are there any other options for setting
the background image on a widget using an in-memory image?

Thanks,
Bogdan & Silenio