Bug 218138

Summary:	MouseEvent.offsetX/Y: Caching of values may create unexpected results
Product:	WebKit	Reporter:	Noam Rosenthal <noam>
Component:	UI Events	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified

Description Noam Rosenthal 2020-10-23 14:58:58 PDT

See https://github.com/w3c/csswg-drafts/issues/1070
Currently, offsetX/Y are computed at the first time they are requested rather than when the event is dispatched.
This means that if there is a layout between the time of the event and the time of the call to event.offsetX/Y, the results would not match the spec, and may also create an undesired synchronous layout.

Comment 1 Radar WebKit Bug Importer 2020-10-30 14:59:15 PDT

<rdar://problem/70898493>