Affected versions

• Firefox ESR 91.0
• Firefox 91.0
• Firefox 92.0a1

Affected platforms

• Windows 10
• macOS 10.15
• Ubuntu 20.04

Steps to reproduce

1. Launch Firefox
2. Download and open this embedded test
3. Hover over - and + icons in each iframe

Expected result

• The zoom icons are visible all the time

Actual result

• Hover state over the zoom icons makes them disappear

Regression range

• Will see for a regression

Additional notes

• The issue can be seen in the attachment

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=a290c08cb41e0617d7384c9e0f517fec32671e29&tochange=7ebb4235a61b066cd1ca3408a80af548b1165421

Brendan, does it ring a bell?
thanks

Alice, thanks for the regression window

Pretty sure this was regressed by the high contrast implementation. I haven't had time to dig into why yet though.

This bug was fixed by
Bug 1726550 - Fix hover style for about:privatebrowsing primary button; both regular and HCM r=pdahiya
Differential Revision: https://phabricator.services.mozilla.com/D126136
pushlog_url: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=ddc9c3bd501e61c79729416bdd270d4b6b76fa31&tochange=5938c983ab44a2b494e0a3e41f11dc2541016a37

Works for me with Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:97.0) Gecko/20100101 Firefox/97.0 Build: 20211226092042

Bug 1731138 is what fixed this (which makes a lot more sense since bug 1726550 only touched privatebrowsing files).