Setup context menu.

def setup_menu(self):
        """Setup context menu."""
        copy_action = create_action(self, _('Copy'),
                                    shortcut=keybinding('Copy'),
                                    icon=ima.icon('editcopy'),
                                    triggered=self.copy,
                                    context=Qt.WidgetShortcut)
        functions = ((_("To bool"), bool), (_("To complex"), complex),
                     (_("To int"), int), (_("To float"), float),
                     (_("To str"), to_text_string))
        types_in_menu = [copy_action]
        for name, func in functions:
            slot = lambda func=func: self.change_type(func)
            types_in_menu += [create_action(self, name,
                                            triggered=slot,
                                            context=Qt.WidgetShortcut)]
        menu = QMenu(self)
        add_actions(menu, types_in_menu)
        return menu