Flet windows don't open centered by default, which is quite annoying

[chenyyoung]

Hey, could the default Flet window appear centered on the screen at startup instead of in the top-left corner? When using page.window.center(), I notice the window flickers from the top-left to the center during launch, which isn't a smooth experience

[ndonkoHenri]

Can you please try the latest pre-release and let know if you still see an issue?

[chenyyoung]

I installed Flet version 0.70 in a UV virtual environment. After launching the program, the window does not center automatically—adding page.window.center() doesn’t help either. In version 0.28.3, that same line of code would correctly center the window, even though the transition from the top‑left corner to the center wasn’t perfectly smooth. Unfortunately, version 0.70 doesn’t seem to natively support window centering, and it still has a few bugs… Still, I love Flet and truly wish it all the best.

[RezaErfani67]

i'm testing with version 0.8.0 and bug stil exist.

 page.window.center()

[ndonkoHenri]

You need to use await page.window.center(), as mentioned in your terminal.

[oktl]

If you haven't figured it out yet this works for me. Make your main async and then after everything is loaded await page.window.center.
Works on macOS, haven't tried Windows or Linux.

async def main(page: ft.Page) -> None:
    """Initialize and configure the main application page.

    Sets up window dimensions, theme, padding, and initializes the application
    state and UI components. Attaches event handlers and centers the window.

    Args:
        page: The Flet page object representing the application window.
    """
    try:
        # Set up logging first thing.
        setup_logging()
        logger.info("Starting application")

        # Configure page-level settings including window size, colors, and title.
        page.title = "Flet test"
        page.window.width = 750
        page.window.height = 1360
        page.padding = 30

        settings = load_settings()
        state = AppState(settings=settings)
        page.theme_mode = (
            ft.ThemeMode.DARK if state.is_dark_mode else ft.ThemeMode.LIGHT
        )
        controls = build_main_view(page, state)
        page.add(controls)

        attach_handlers(page, state)

        await page.window.center()

    except Exception as e:
        logger.error(f"Application error: {e}")
        logger.exception("Full traceback:")
        raise


def run() -> None:
    ft.run(main, assets_dir="assets")


if __name__ == "__main__":
    run()

[ndonkoHenri]

In the latest versions, use await page.window.center(), with your main function being async.
If you need to hide the window before doing this, see this example.