Function on_pre_window_load 

pub fn on_pre_window_load(
    child: impl IntoUiNode,
    handler: Box<dyn FnMut(&WindowOpenArgs) -> HandlerResult + Send>,
) -> UiNode

P On window loaded.

This event notifies once per window, after the first layout and all WindowLoadingHandle have expired or dropped.

If the window has a renderer this event notifies only after the window is loaded with renderer in the view-process.

Route

This event property uses the preview route, that is, the handler is called before the children widget handlers and before the $pn_ident handlers.