Err... Excuse me yes you are correct it isn't the point of the topic however I do not contradict myself and I would like you to realise what I am saying. I will explain what I have said in a different way (this does not mean I will contradict (negate) myself):
From a user's perspective it is not good practise to stop the user from using the browser's navigation system because this effects their overall web experience. However, this is exceptable if the page is for example:
- an image enlargement
- a more detailed product description
- or something that is small and does not require the full width and height of the page.
The reason for this is that the average user may not notice that a pop-up has appeared and will then feel lost because their normal browser does not look normal! They will then have no way of navigating away from the page apart from closing it. Whereas, if it is a smaller window the user can see what is behind it and can still see how to navigate away from the specific page.
The main aim of general web design is to keep the user happy and to have good "usability" on your website. For this reason, it is not good practise to pop up a full screen window with no navigation bars.
I truely hope that this has cleared this whole argument up. You must understand that my comments are coming from a ergonomic view and not a technical view.