Is that possible to put action, message handler, and other functions in another file?

[Tim-Cao]

Imagine there are lots of action, message handler, and other functions in App file. It's hard to read and maintain.
Is that possible only keep widget compose in App file?
For example,

    def compose(self) -> ComposeResult:
        yield Sidebar(classes="-hidden")
        yield Header()
        with Horizontal(id="main-content"):
            yield ListView(
                ListItem(Nav_Item("Forward Failure PR"), id="nav-1"),
                ListItem(Nav_Item("Create PR and Forward"), id="nav-2"),
                ListItem(Nav_Item("Create TF Ticket"), id="nav-3"),
                ListItem(Nav_Item("Write Comments"), id="nav-4"),
                ListItem(Nav_Item("Write Description"), id="nav-5"),
                ListItem(Nav_Item("Trigger Gauntlet"), id="nav-6"),
                ListItem(Nav_Item("Create Issue"), id="nav-7"),
                ListItem(Nav_Item("RCA"), id="nav-8"),
            )


class Output(RichLog):
    @on(events.Print)
    def on_print(self, event: events.Print) -> None:
        if event.text.strip():
            self.write(event.text)


app = ScriptApp()

if __name__ == "__main__":
    app.run()

    def on_button_pressed(self, event: Button.Pressed) -> None:
        if event.button.id == "button-1":
            self.forward_failure_pull_request()
        elif event.button.id == "button-2":
            self.create_pr_and_forward()
        elif event.button.id == "button-3":
            self.create_test_fix_ticket()
        elif event.button.id == "button-4":
            self.write_comments()
        elif event.button.id == "button-5":
            self.write_description()
        elif event.button.id == "button-6":
            self.trigger_gauntlet()
        elif event.button.id == "button-7":
            self.create_issue()
        elif event.button.id == "button-8":
            self.conversion()

    def on_list_view_selected(self, event: ListView.Selected) -> None:
        self.query_one(ContentSwitcher).current = event.item.id

    @work(exclusive=True, thread=True)
    def action_open_credentials(self) -> None:
        self.query_one(RichLog).clear()
        self.query_one(RichLog).begin_capture_print()

        credentials.open_credentials()

    @work(exclusive=True, thread=True)
    def action_sync_components(self) -> None:
        self.query_one(RichLog).clear()
        self.query_one(RichLog).begin_capture_print()

        jira_components_sync.main()

    @work(exclusive=True, thread=True)
    def action_toggle_sidebar(self) -> None:
        sidebar = self.query_one(Sidebar)
        self.set_focus(None)
        if sidebar.has_class("-hidden"):
            sidebar.remove_class("-hidden")
        else:
            if sidebar.query("*:focus"):
                self.screen.set_focus(None)
            sidebar.add_class("-hidden")

[Tim-Cao]

#3675