'If this is the first time the plugin is shown, perform actions to
initialize plugin position in Spyder\'s window layout.
Use on_first_registration to define the actions to be run
by your plugin'

def initialize_plugin_in_mainwindow_layout(self):

    if self.get_option('first_time', True):
        try:
            self.on_first_registration()
        except NotImplementedError:
            return
        self.set_option('first_time', False)
