In Mathematica, almost everything is notebook: your "Untitled-1.nb" is a notebook, Help documentation are a series of notebooks, even those windows helping you to draw things or format your notebooks are, themselves, notebooks.
But I occasionally find some exceptions and I want to know what are they.
Run the following code and then open new palettes or notebooks, new names will bump out, but when opening the "Preference" window or "Enter Activation Key" window, nothing will happen.
Dynamic[Notebooks, UpdateInterval -> 1]
Are they specially formatted and styled notebooks or some wierd things other than notebooks which are constructed using more basic form of programming? How can we know what's the content of them using something like