[Gtk-sharp-list] Restoring default Gdk.Color for widgets

[Leo Spalteholz]

I was trying to restore the default color for a widget and ran into some 
problems.  
In the Gtk.Widget docs for ModifyBg it says:
<param name="color">The color to assign (does not need to be allocated), or 
<see langword="null" /> to undo the effect of previous calls of <see 
cref="M:Gtk.Widget.ModifyBg" />.</param>

But when I try this:
myWidget.ModifyBg(StateType.Active, null);
I get the following compilation error:
Common.cs(49) error CS1503: Argument 1: Cannot convert from 'object' to 
'Gdk.Color'

Any ideas on how to restore the default widget color are appreciated.

Thanks,
Leo