'Return the GdkPixbuf icon according to \'os\' paramather string
and a str_id to that GdkPixbuf for easy comparison and ordering
of the view (\'os\' paramether string is complicated and has caps).'

def __decide_icon(self, os):

    os = (os.lower() if os else '')
    if (('linux' in os) or ('unix' in os)):
        icon = GdkPixbuf.Pixbuf.new_from_file(self.linux_icon)
        str_id = 'linux'
    elif ('windows' in os):
        icon = GdkPixbuf.Pixbuf.new_from_file(self.windows_icon)
        str_id = 'windows'
    elif ('mac' in os):
        icon = GdkPixbuf.Pixbuf.new_from_file(self.mac_icon)
        str_id = 'mac'
    else:
        icon = GdkPixbuf.Pixbuf.new_from_file(self.no_os_icon)
        str_id = 'unknown'
    return (icon, str_id)
