Originally Posted by kacir
The vast majority of other readers work like this:
They count how many pages (understand screen-fulls) they need to display the book using current font size, margin size, line space, hyphenation setting, and other format options. Then they display "You are on page 160 of 320". If you change the font size or other option the page number gets updated to "you are on page 250 of 500". Problem solved.
This is incorrect. The "vast majority of other readers" are ePub devices which use ADE to display books. ADE's page numbers are a count of 1024 characters in the compressed file, which typically means that the same page number is displayed for several screens on the reader.