Fix: Page length change will now attempt to keep the start point on the current page, but will shift that row's position away from the start point, so that the paging is always consistent in its display. Without this changing the page length could result in landing on page "1.4" (or some other partial page) that you could never get to with just paging alone. That is no longer possible in DataTables.

This is something that has been in DataTables since the version first
vresion and was contentious at that point so while this is a minor code
change, for me it is quite a big change! I feel that this is the correct
operation now, although it does result in rows being moved around where
they might not be needed to if partial pages could be used.