ShowAsyncQueue

This Extension can fix following error:

NOTE

Only one ContentDialog can be shown at a time. To chain together more than one ContentDialog, handle the Closing event of the first ContentDialog. In the Closing event handler, call ShowAsync on the second dialog to show it.

contentDialog.ShowAsyncQueue();

ShowAsyncDraggable

contentDialog.ShowAsyncDraggable();

ShowAsyncQueueDraggable

contentDialog.ShowAsyncQueueDraggable();

Demo

you can run demo and see this feature.