Nautilus themes and highlight_color_rgba

[Federico Mena Quintero <federico ximian com>]

Hi,

So with my recent fix for #82194, it turns out that none of the current
Nautilus themes specify the "highlight_color_rgba" attribute for
directory lists.  This means that the code will fall back to the color
in style->base[GTK_STATE_SELECTED] from the current GTK+ theme, making
most Nautilus themes look ugly.

[The old code had a fallback to semiopaque gray, but it would break if
you *did* specify a color on your own, paining things incorrectly in
that case.]

I guess the Nautilus themes need to be fixed so that they do specify a
color of their own.

  Federico