[gtkada] Set_Foreground

[Manuel Op de Coul]

Thanks to Preben's asking on the gtk list this mystery has been cleared 
up. So it's possible to set the entry colour, only it's not 
possible in GtkAda 2.2.0.
Because the function gtk_widget_modify_fg hasn't been provided yet.

Normally it's all "set" and "get" so I don't know why this is called
"modify". So when these functions are bound, could the names be the
same as in Gtk.Style?

Manuel