Or is there a way to cast them to winrt::Microsoft::UI::Xaml::Window?
If not, does that mean I have to do the following things with the help of some custom classes applied to manage extra windows?
https://learn.microsoft.com/en-us/windows/apps/windows-app-sdk/system-backdrop-controller
So far, I'm able to invoke a new window through declaring Window object and setting the content from a XAML. But it's sort of inconvenient and limited for my part.