1726811 - Setting accessibility.tabfocus in mochitest test might not change the focus behave on Mac

Status: NEW

(Core :: DOM: UI Events & Focus Handling, enhancement, P3)

Description

[Edgar Chen [:edgar]]

Found this while working on https://bugzilla.mozilla.org/show_bug.cgi?id=1723010#c13.
You can reproduce the issue via

• Disable "Use keyboard navigation to move focus between controls" on Mac, see https://support.apple.com/en-us/HT204434.
• run ./mach test dom/events/test/test_accesskey.html dom/events/test/test_bug226361.xhtml

The issue is around https://searchfox.org/mozilla-central/rev/12770bd668c0a6bdaa8eb96ad9507c6febe8d23d/dom/base/nsFocusManager.cpp#3279,

• The first test, test_accesskey.html, make LookAndFeel cache the current setup (eTabFocus_textControlsMask).
• The second test, test_bug226361.xhtml, sets accessibility.tabfocus to 7, but the LookAndFeel still has the old cache value for a while which makes test_bug226361.xhtml failed.