Bug 274903 – WebKit disagrees with other browser on z-index handling with ib-splits

• Status: NEW
• Component: Layout and Rendering

[Daniel Holbert]

STR:
1. Load testcase 1: https://bug1573990.bmoattachments.org/attachment.cgi?id=9085605
or testcase 2: https://bug1573990.bmoattachments.org/attachment.cgi?id=9085608
...from https://bugzilla.mozilla.org/show_bug.cgi?id=1573990
2. Compare to Firefox and Chrome.

ACTUAL RESULTS (in Safari):
In testcase 1, Safari renders the orange area with text in the foreground (visible).
In testcase 2, Safari renders the orange area with text separately (it's not blurry).

EXPECTED RESULTS (in Firefox/Chrome):
In testcase 1, Firefox/Chrome don't show the orange area with text (it's covered up)
In testcase 2, Firefox/Chrome include the orange area with text as part of the blur.


NOTES:
I haven't dug into the spec, and the details here are weird because IB splits are weird, but at least from an interop perspective:

It seems Chromium used to match WebKit on this and they changed between Chrome 100 and 101, presumably due to considering the old behavior a bug.   So now WebKit is alone on the ACTUAL RESULTS here, and Gecko/Blink (and even pre-Chromium EdgeHTML) match EXPECTED RESULTS here.

[Radar WebKit Bug Importer]

<rdar://problem/129344145>