873313 - incorrect/random rendering/layout at some font-size dependent position

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect)

Description

[Vincent Lefevre]

Attachment: Testcase

The best way to see the bug is to open http://www.lebardegandi.net/post/2013/04/25/L-IaaS-va-passer-en-paiement-à-la-consommation while having the Stylish extension with the following global style:

@namespace url(http://www.w3.org/1999/xhtml);
html { font-size: medium !important }

Go near or at the end of the page. What is displayed depends on what was displayed before hitting the [End] key. Moving the mouse may be sufficient to make the black background appear. There are some screenshots here:

  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=707187#10

(for Debian's Iceweasel, but the bug is reproducible with Firefox Nightly). In practice, this makes a large part of the page unreadable.

I've also attached a standalone testcase base on an older version of the above page, on which I added the above style and did some clean-up for the test (such as removing scripts and images), so that no extensions are needed (I've tried on an almost-clean profile). The bug is less visible with Firefox Nightly, but by playing with the PageUp / PageDown / Ctrl+ and Ctrl- keys, I could make it appear.

Comment 1

[Vincent Lefevre]

After doing some more tests on the http://www.lebardegandi.net/post/2013/04/25/L-IaaS-va-passer-en-paiement-à-la-consommation page without any extension, I could reproduce the bug, but the problem doesn't appear at the end of the page, but around messages 114-116. But if I do a Ctrl+ to increase the size of the fonts, it appears around messages 100-101. So, I suppose that where the problem appears depends on the font size. It might appear at some given number of pixel-lines.

Comment 2

[Alice0775 White]

This is caused by landing bug 562746 when HWA disabled and/or blcked

Comment 4

[u279076]

Does this bug reproduce in the current Firefox Nightly?

Comment 5

[Loic]

I'm able to reproduce it with FF21, but not with FF25 (and ofc FF48), so it has been probably fixed 2 years ago.

Comment 6

[Vincent Lefevre]

I can't reproduce this bug with Firefox 45.3.0. I assume that it has been fixed.