UWP on desktop closed by top X button - no event

Question

An UWP app which runs on desktop can be closed from the top X button but it doesn\'t have any event for it. It is known that on phones and tablets an app should rely on

Answer 1

A restricted capability confirmAppClose was added in Windows 10 version 1703 (build 10.0.15063) in order to provide apps the ability to intercept window closing.

Manifest namespace:

xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"

Manifest:

It needs extra approval when submitting to the store. But then will fire the CloseRequested event on a SystemNavigationManagerPreview instance.

Code:

    public MainPage()
    {
        this.InitializeComponent();
        SystemNavigationManagerPreview.GetForCurrentView().CloseRequested += this.OnCloseRequest;
    }

    private void OnCloseRequest(object sender, SystemNavigationCloseRequestedPreviewEventArgs e)
    {
        if (!saved) { e.Handled = true; SomePromptFunction(); }
    }

You can get a deferral to do a bit of work here (save or prompt), or you can set Handled to true in order to stop the window from closing (user cancelled prompt).