STR:

1. Open https://www.mozilla.org/en-US/firefox/82.0a1/whatsnew/all/?oldversion=81.0a1
2. Ctrl+P

Actual Results:
"2 sheets of paper" in dialog header.
However, prepiew has 3 sheets.

Expected Results:
Both should be same

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=bbc6744b3ca2f9b902c30bbb8c99965563421c5b&tochange=18dbcec715c7f176ef13c30579efd5603148c4de

I only see two sheets of paper fwiw, so may depend on the fonts on the system or what not... Hiro you've been doing our print preview page count stuff, maybe you can look at this?

Thanks a lot for filing Alice :)

I suppose this is a dup of bug 1658819.

I'd say we haven't been handling the number properly in the new print preview in the first place. And reasons showing incorrect number are depending on various factors (in my case, it was print.print_paper_height value), so presumably the change in bug 1414600 did affect the factor in Alice's environment.

Anyways, let's wait for Mark's work in bug 1658819.

Alice, would you mind trying to see whether the issue still persists on the latest nightly?
Thanks!

Reproduced on Nightly82.0a1(20200825094622)
And I verified fix on Nightly82.0a1(20200826032437).

Thank you, Alice! Let's dup then. :)