Always define theme background and text colors?

[Milan Crha <mcrha redhat com>]

        Hi,
I'm trying to investigate bug [1], where Evolution reads theme color
with gtk_style_context_get_background_color() and
gtk_style_context_get_color(), which are, from my point of view, the
only functions to get a base color of the theme (like for a plain
GtkWindow, or GtkLabel,...). These are used to define text and
background color of a WebkitGtk3's web view, to have the page look as
close to the theme as possible. Because it's an HTML page, then one
cannot use gtk_render_background() or similar functions, thus the code
currently relies on colors provided by a theme.

This works fine for some themes, but does not for others, like for the
default Gnome theme Adwaita, which claims a black background with white
text color, even the window color is gray. I guess (but I do not know
for sure), that Adwaita doesn't define background and text color,
because the background is an image, instead of a plain color.

Due to all the above, and quite inconsistency, I believe that it's a
good thing for any theme to also define colors for background and
foreground, regardless the respective widget has defined an image as
background or not (if a widget doesn't overwrite a background or
foreground, then it doesn't need these colors defined).

What do other people think, please?
        Bye,
        Milan

P.S.: I'm not subscribed to this list, please keep me in CC.

[1] https://bugzilla.gnome.org/show_bug.cgi?id=699576