'Implement this method and :meth:`save_settings` in your plugin to
use a custom configuration dialog.
This method, if implemented, must return a QWidget. The widget can have
an optional method validate() that takes no arguments and is called
immediately after the user clicks OK. Changes are applied if and only
if the method returns True.
If for some reason you cannot perform the configuration at this time,
return a tuple of two strings (message, details), these will be
displayed as a warning dialog to the user and the process will be
aborted.
The base class implementation of this method raises NotImplementedError
so by default no user configuration is possible.'

def config_widget(self):

    if self.actual_plugin_:
        from calibre_plugins.obok_dedrm.config import ConfigWidget
        return ConfigWidget(self.actual_plugin_)
