Discussion: Should ContentDialog in a Desktop WinUI 3 app create a modal top-level window?

Today, the ContentDialog is just XAML content placed on the top of the visual tree. In WPF, ContentDialog is like a MessageBox, which is a modal top-level child window.

Discussion: Should the ContentDialog pivot towards a modal top-level child window?

In this way, ContentDialog won’t need XamlRoot anymore. There are several customer complains that the need of XamlRoot is unintuitive for WPF/Win32 developers (e.g. #2504)

There are several questions that need to be answer:

1. What parent XAML Window will host the ContentDialog top-level child window. Desktop WinUI 3 apps can have multiple Window objects in the same thread. So, do we need new APIs? For example:

 contentdialog.ShowAsync(mywindow); 

1. How will the new top-level child ContentDialog work with the RequestedTheme feature?

2. Will the new ContentDialog work in XAML Islands scenarios? Will be still needed XamlRoot for Islands?

[mdtauk]

Not directly related, but perhaps relevant for the future… #885 #2313 (My own Task Dialog proposal)

Whatever modal top-level window is coded/designated for this - could it be extended to other future modal control proposals?

[mdtauk]

There was a topic about looking at Content Dialog dismissal behaviour #2122 which perhaps could be a behaviour property of the ContentDialog.

That way it could render within the window with Light Dismiss. Include as default, the current behaviour, and add a ModalWindow option, which will create a movable window with only a Close button, or Close and Minimise.

ContentDialog.Behaviour - LightDismiss
                        - Overlay
                        - Modal