Dear Nermander
First of all, I apologise.
My criticism was harsh and wrong -- it was born of frustration rather than disrespect -- and I spoke from inexperience.
My point was this:
When it's left first, the pages are displayed side-by-side an butted up to each other, which is exactly as it would be in a book and is easy to handle on a wide screen -- I can see both pages at once.
Right first is the layout of, for example, a single sheet within a book -- in left-to-right reading countries, you read the right-hand page first and then turn the page. However, when my document has only two side, I would still like to be able to see both pages at once. Of course, in this case, it would be appropriate for there to be a gap between them to indicate that the right edge of the right page does not but up to the left edge of the left page.
Putting it simply, I want to be able to use the width of my big screen.
But I agree that the way Scribus does it is correct.
Yours contrite and in friendship
Alan