The code

from enthought.traits.api import *
from enthought.traits.ui.api import *
from enthought.traits.ui.menu import Action, Menu, MenuBar

class MainHandler(Handler):

    def init(self, info):
        actions = [Action(name='Load file', action='load_file'),
                   Action(name='Save file', action='save_file'),
                   Action(name='Save as file', action='saveas_file'), ]
        info.ui.view.menubar = MenuBar(Menu(*actions, name='File'))
        info.ui.updated = True

class MainWindow(HasTraits):

    a = Float
    b = Float

    view = View('a', 'b')

if __name__ == '__main__':

    MainWindow().configure_traits(handler=MainHandler)