'Open the store.
:param gui: The main GUI. This will be used to have the job
system start downloading an item from the store.
:param parent: The parent of the store dialog. This is used
to create modal dialogs.
:param detail_item: A plugin specific reference to an item
in the store that the user should be shown.
:param external: When False open an internal dialog with the
store. When True open the users default browser to the store\'s
web site. :param:`detail_item` should still be respected when external
is True.'

def open(self, gui, parent=None, detail_item=None, external=False):

    raise NotImplementedError()
