new_contents: from gi.repository import GObject
  
  class TData(GObject.GObject):
  
      imagedir           = GObject.property(type=str)
      lasttrackfolder    = GObject.property(type=str)
      tracktimezone      = GObject.property(type=str)
      alwaysthistimezone = GObject.property(type=bool, default=False)
      markersize         = GObject.property(type=int)
      trackwidth         = GObject.property(type=int)
  
      def __init__(self):
          GObject.GObject.__init__(self)
  
      def connect_signals(self, handlers):
          for prop, handler in handlers.items():
              self.connect("notify::%s" % prop, handler)
  
  GObject.type_register(TData)
  
subject: Add TData class implementing GObject.GObject, meant for runtime data storage