Function with_refresh 

pub fn with_refresh<E: Serialize>(
    widget: Widget,
    refreshing: bool,
    on_refresh: E,
) -> Widget

Enable pull-to-refresh on a scaffold’s body: the body becomes pull-refreshable and fires on_refresh on pull. refreshing is app-owned — set it true when the pull fires and clear it when the async reload completes (the shell shows a spinner while true). No-op on other widgets.