When using the DialogService (or the PopupService), you must pass either a TemplateRef or a Component class to the content property for it to create.  However, if you have a Component that needs special initialization (i.e. constructor parameters) or that you have already created using a factory, you cannot use that as the content for the DialogService/PopupService.  This feature request is to allow the content parameter to be valid if an existing component instance (already created) is passed.