class_docstr: A list of checkboxes with extra annotation, and a context menu.
  
  Designed as an alternative to NameSubscriberCombobox which simplifies selection of
  multiple items.
code: def add_callback(self, cb):
      self.callbacks.append(cb)
  
imports: import platform
  import wx
label_desc: Use image node_id 2 for calling the NameSubscriberListBox obj's underlying member method code with example usage: obj.add_callback(cb) without return types