We will not do keyboard APZ, even if the event listener is marked passive. Passive only restricts the use of preventDefault, and we also care about whether the event listener changes the focus or selection of a page.
An example where this matters would be a page with a key listener that sets the focus of the page to a <textarea>. If the user were to hit space twice, they would expect the first space to scroll the page, and the second to be input into the <textarea>. With keyboard APZ enabled we can't guarantee that to happen, as the focus of the page can't be guaranteed to sync to APZ in time for us to know not to scroll the root scroll frame again. It's not clear whether this is behaviour that is widely relied on. We're attempting to be conservative in the cases we allow this. Let me know if the example is unclear. Thanks, Ryan ________________________________________ From: Ben Kelly <[email protected]> Sent: Sunday, July 23, 2017 12:26 PM To: Ryan Hunt Cc: [email protected] Subject: Re: Keyboard APZ has landed on Inbound On Sat, Jul 22, 2017 at 2:05 AM, Ryan Hunt <[email protected]<mailto:[email protected]>> wrote: Keyboard APZ can't be used in every case. Currently it's disabled in the presense of key event listeners, as they can preventDefault scrolling and that is a non-negotiable part of the web. Do we do keyboard APZ if the event listener is passive:true? _______________________________________________ dev-platform mailing list [email protected] https://lists.mozilla.org/listinfo/dev-platform
