Change GtkTreeViewColumn header background color

[Gabriele Greco <gabriele greco darts it>]

There is an easy way to do it, a rc option would be very nice but I've 
not found it!

Adding a custom object as column header is not ok, since you get your 
background only under the label (the border and the arrow keep the old 
background).

Lurking in the sources I've found this way, but it's way too 
implementation dependant:

    GtkWidget *l = gtk_label_new(title.c_str());
    gtk_widget_show(l);
    gtk_tree_view_column_set_widget(col, l);
    GtkWidget *w = gtk_tree_view_column_get_widget(col);

    // From the sources this is the object hiearchy:
    //   get_widget object -> alignment -> hbox -> button

    GtkWidget *b = w->parent->parent->parent;

    GdkColor bg;
    gdk_color_parse("#b8b8b8", &bg);
    gtk_widget_modify_bg(b, GTK_STATE_NORMAL, &bg);


--
Bye,
 Gabry