Consider the following case.

I want to print some slides. These are landscape and with a very big font. Excellent candidate for putting multiple slides on a single sheet of A4 paper.

I open the slides in okular, I select "print", the print dialog opens. I press options, to get more printer options and I go to the "pages" pane. Here, I have a "pages per sheet" sub-pane.

Already there is something wrong: the "6", "9" and "16" pages per sheet have no icon and a "?" appears in place of the icon. Looks bad, but no real issue.

Suppose that I want to get 6 slides on each A4 page, arranged in the following order

1      2
3      4
5      6

So I select "6" pages per sheet and "Left to Right, Top to Bottom" order. Right? Not at all.
To get the correct slide order in print, I need to select "Bottom to Top, Left to Right". This is very confusing to the user.

However, I believe that it has a simple explanation and a trivial fix. I believe that this comes from the fact that the slides are landscape and that the page on which I print is portrait, so that there is an implicit rotation.  Unfortunately, the order selector seems to ignore this implicit rotation.  

Reproducible: Always