I've begun looking into this and there is a non-trivial problem to solve in
to know the number of pages available for printing you need to know which
printer and page the user is going to print onto. Thus you need the results
the user's printer selection to calculate the documents size, but you don't get
that till you have clicked ok on the dialog.
Chicken and egg problem. I think I'll end up guessing. But that means rewriting
a bunch of code. So this won't make it into test3, but test4 would be a good
target for release.
Now the selection of the printing range is possible, however it does not work
properly, because the whole email is printed.