I have no idea if this is feasible but could we prevent extensions from performing synchronous layout flushes before layout has started? If this is possible, extensions that need to perform them could require a new permission?
Another alternative, can we prevent extensions from injecting content in webpages before layout has started? > On 1 Sep 2017, at 22:57, Ehsan Akhgari <ehsan.akhg...@gmail.com> wrote: > > FWIW I filed https://bugzil.la/1396097 for adding a console warning which > would have warned about this specific case. > > > On 09/01/2017 12:37 PM, Boris Zbarsky wrote: >> On 8/31/17 3:00 PM, Michael Froman wrote: >>> If I disable Ghostery, it no long appears to happen for me. YMMV. >> >> Michael, >> >> Thank you. So with Ghostery installed, I managed to reproduce a flash of >> unstyled content when doing a force-reload of https://github.com/servo/servo >> >> That's because Ghostery does a .clientHeight get with this stack: >> >> 0 setBoxHeights() >> ["moz-extension://8ecb1f2d-060f-ce44-96ed-44895f11ca4b/dist/purplebox.js":128] >> 1 handleMessages(request = [object Object], sender = [object Object]) >> ["moz-extension://8ecb1f2d-060f-ce44-96ed-44895f11ca4b/dist/purplebox.js":448] >> >> (the rest is less important). >> >> I reported this issue to them (copy/paste of my report below) through the >> form at https://ghostery.zendesk.com/hc/en-us/requests/new but if someone >> has better contact info that might be nice. >> >> -Boris >> >> Report I sent: >> >> STEPS TO REPRODUCE: >> >> 1) Install Ghostery in Firefox. >> 2) Load https://github.com/servo/servo/ >> 3) Force-reload a few times. >> >> ACTUAL RESULTS: Eventually you get a flash of unstyled content: content >> being rendered before the stylesheets are loaded. >> >> EXPECTED RESULTS: No flashes of unstyled content. >> >> DETAILS: The flash of unstyled content is due to Ghostery forcing a layout >> before the stylesheets are loaded. This happens when the setBoxHeights() >> function, in purplebox.js is called from handleMessages(), which is handling >> the 'createBox' message. >> >> setBoxHeights does this: >> >> windowHeight = doc.documentElement.clientHeight * 0.85 - 35; >> >> which forces layout of "doc" which in this case is the webpage being loaded. >> If all you want is the height of the window that document is in, possibly >> with some adjustments, you could use `doc.defaultView.innerHeight`, or >> `win.innerHeight` if "win" is the window for "doc". The innerHeight getter >> doesn't need to perform layout within the window itself, and won't cause >> this problem. >> >> It might also be possible to not do 'createBox' until layout has started on >> the page. I'm not sure that point in time is exposed to extensions at the >> moment, but we might be able to add a notification that exposes it. What I >> don't know whether that's a viable option in your case; it's possible that >> you need 'createBox' to happen before that point. >> _______________________________________________ >> dev-platform mailing list >> dev-platform@lists.mozilla.org >> https://lists.mozilla.org/listinfo/dev-platform > > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
