On Wed, Dec 6, 2023 at 5:08 PM Mustaq Ahmed <[email protected]> wrote:
> > I assume cancelling the mousedown (but not the mousemove) still prevents > selection and drag-and-drop in all browsers, is that right? That's the > pattern I'd expect is most common. Also, what's the behavior of pointermove > for mice today and after this change? > > I just confirmed <https://codepen.io/mustaqahmed/full/wvNYGEP> that > Chrome (and Firefox and Safari too) already prevents both selection and > drag-and-drop when mousedown or pointerdown is cancelled. So sites > canceling all the mouse events will work fine. > Great, thanks! That definitely lowers my concern. > We have landed a metric which specifically checks for cases where the > mousemove is preventDefaulted but a selection starts (i.e. selectstart > wasn't prevented, there was no user-select: none, and so the selection does > change). Right now this is a UMA but we could also add UKM and get sites > from this. Mustaq WDYT about adding UKM for this and running the 1% finch > trial? > > Adding UKM and running a 1% finch trial sounds good. > > Perhaps we can run a Canary/Dev/Beta trial even now (on M121)? > Yep, you can do whatever you want for canary/dev and you have API owner approval for Beta and Stable up to 1% if you want it. Perhaps beta data alone would be compelling enough for API owners to approve this (with an understanding, like always, that we'd kill-switch it on reports of non-trivial stable breakage). On Wed, Dec 6, 2023 at 12:34 PM Robert Flack <[email protected]> wrote: > >> On Wed, Dec 6, 2023 at 12:18 PM Rick Byers <[email protected]> wrote: >> >>> API owners met and discussed this one briefly today. There was agreement >>> that more work needs to be done to demonstrate the compat risk is low >>> enough to ship this breaking change. A few points: >>> >>> - If you'd like to do a finch trial to gather data (up to stable 1%) >>> we're supportive of that. >>> - Mike Taylor argued that you're not likely to learn too much useful >>> from a finch trial since people seem not to report bugs for things that >>> fail for a seemingly random 1% of their users, and perhaps the idea of >>> surveying a few sites would be more effective at finding real breakage. >>> Of >>> course UKM + Finch might be a good way to find URLs to test. >>> >>> We have landed a metric which specifically checks for cases where the >> mousemove is preventDefaulted but a selection starts (i.e. selectstart >> wasn't prevented, there was no user-select: none, and so the selection does >> change). Right now this is a UMA but we could also add UKM and get sites >> from this. Mustaq WDYT about adding UKM for this and running the 1% finch >> trial? >> > Ah that makes sense. Sorry I only took a quick glance at the code for the UseCounter and missed that. That's indeed much more relevant than I was thinking, maybe it won't be so high after all and that can give us good confidence to ship? > >>> - Mike also argued that in his experience, he'd expect sites like >>> mapping apps to have engine-specific conditional code around their event >>> handling, so that increases the risk. >>> - Philip and I discussed that if there is evidence of real breakage >>> we can't accept, we should propose changing the spec here - it seems like >>> it would be very reasonable if cancelling the first mousemove event in a >>> sequence canceled text selection (just like cancelling the first >>> touchmove >>> prevents scrolling). But if we have reasonable evidence that it's >>> non-breaking, we're happy to just align with WebKit and Gecko for >>> improved >>> interoperability. >>> >>> Agreed, though it may be breaking for other engines to change behavior >> too though, right? E.g. we are in a similar situation with >> overscroll-behavior on the root element (crbug.com/954423 >> <https://bugs.chromium.org/p/chromium/issues/detail?id=954423&q=overscroll-behavior%20root&can=2>) >> where changing either behavior to the other will have compat risk. >> > Oh good point. And breaking intended selection is arguably worse than allowing unintended selection. Ok, that's a further argument for us accepting more risk here, thanks. > >>> - All agreed we're willing to take some risk here to achieve interop >>> quickly and don't want to impose too much of a burden of proof, >>> especially >>> since the severity of breakage is likely low. We just need some more >>> evidence that the risk is manageable. >>> >>> Perhaps the most pragmatic path would be something like: >>> >>> 1. Survey at least 5 sites with mouse drag involving DOM and explain >>> why they're unimpacted (cancelling mousedown? cancelling selectionstart? >>> or >>> just user-select: none?). If you find one that is indeed broken, revisit >>> plan. >>> 2. Work with the enterprise team on release notes & plan - i.e. >>> either finch roll out with commitment to killswitch if we get reports of >>> enterprise breakage, or add a policy knob opt-out >>> 3. Go for 100% but be prepared to killswitch if there are >>> non-trivial reports of breakage, then revisit with either a migration >>> plan >>> (outreach, blog post) or proposed spec change >>> >>> WDYT? >>> >> >> This sounds reasonable. I think running the 1% experiment with the >> targeted metric (cases where selection now happens when it didn't used to) >> should help us gain confidence. >> >> Rick >>> >>> On Tue, Dec 5, 2023 at 3:42 PM Rick Byers <[email protected]> wrote: >>> >>>> Hey Mustaq, >>>> Thanks for pushing to get this long-time interop issue addressed! I >>>> assume cancelling the mousedown (but not the mousemove) still prevents >>>> selection and drag-and-drop in all browsers, is that right? That's the >>>> pattern I'd expect is most common. Also, what's the behavior of pointermove >>>> for mice today and after this change? >>>> >>>> What's your plan for if the UseCounter comes back high? FWIW, I'm >>>> betting that it will. First I expect it'll be common for sites to >>>> cancel all the mouse events. If my understanding above is correct, then >>>> perhaps you want to exclude those from your UseCounter since the behavior >>>> won't change in those cases? But secondly, given past history with some >>>> major sites, I suspect there might be a long tail of sites that are lightly >>>> broken here. Maybe worth doing a finch-based rollout to mitigate the risk? >>>> I'd support going up to stable 1% now to see if we learn of any issues. I'm >>>> particularly worried about enterprise (LOB) apps which are often >>>> chromium-only. We'll see what Enterprise review says on the launch, but >>>> they might want >>>> <https://www.chromium.org/developers/enterprise-changes/> a mention in >>>> the release notes and a policy opt-out. Then again perhaps since the >>>> breakage is likely to be rare and cosmetic, just doing a finch-based >>>> roll-out (and hitting a finch killswitch on reports of any issues) should >>>> be enough to mitigate the risk. >>>> >>>> You might also consider enabling UKM support >>>> <https://source.chromium.org/chromium/chromium/src/+/main:components/page_load_metrics/browser/observers/use_counter/ukm_features.cc?q=ukm_features&ss=chromium> >>>> for >>>> your UseCounter to get some sample URLs, though again I'd worry you might >>>> get lots of hits but not be able to easily reproduce any obvious breakage. >>>> Alternately it might be most useful to just spot check 5-10 major sites >>>> which have mouse dragging behavior with DOM (not just canvas) and catalog >>>> how they avoid getting unintended selection (eg. do they cancel selectstart >>>> or use user-select: none). I think mapping sites are an obvious example, >>>> gmail has some message dragging behavior I think, not sure what else. >>>> >>>> Rick >>>> >>>> On Mon, Dec 4, 2023 at 2:35 PM Mustaq Ahmed <[email protected]> >>>> wrote: >>>> >>>>> Contact [email protected], [email protected] >>>>> >>>>> ExplainerNone >>>>> >>>>> Specificationhttps://w3c.github.io/uievents/#event-type-mousemove >>>>> >>>>> Summary >>>>> >>>>> Canceling mousemove will not prevent text selection or drag-and-drop. >>>>> Chrome allowed cancelling mousemove events to prevent other APIs like text >>>>> selection (and even drag-and-drop in the past). This does not match other >>>>> major browsers; nor does it conform to the UI Event spec: >>>>> https://w3c.github.io/uievents/#event-type-mousemove Through this >>>>> feature, the default-action of mousemove becomes none. Text selection and >>>>> drag-and-drop can still be prevented through cancelling selectstart and >>>>> dragstart events respectively, which are spec compliant and fully >>>>> interoperable. >>>>> >>>>> >>>>> Blink componentBlink>Input >>>>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EInput> >>>>> >>>>> TAG reviewNone >>>>> >>>>> TAG review statusNot applicable >>>>> >>>>> Risks >>>>> >>>>> >>>>> Interoperability and Compatibility >>>>> >>>>> This feature will make Chrome fully interoperable. Chrome is currently >>>>> failing the corresponding WPT (a part of Interop 2023) while both Mozilla >>>>> and WebKit have started passing the WPT recently. There is a bit of compat >>>>> risk. We attempted it twice in the past but had to revert for two >>>>> different >>>>> reasons: in 2014 we faced a text-selection regression >>>>> https://crbug.com/485892 on an app that no longer shows the problem >>>>> (because app event handling changed), then in 2018 we faced a >>>>> drag-and-drop >>>>> regression https://crbug.com/878392 that is irrelevant now (because >>>>> Chrome drag-and-drop changed). For our current attempt the risk from >>>>> text-selection remains, and we need to expose the feature to be able to >>>>> assess the risk. We have added a use-counter and turned on the feature as >>>>> "experimental" on M121 to observe field data before shipping it. >>>>> >>>>> >>>>> *Gecko*: Shipped/Shipping ( >>>>> https://bugzilla.mozilla.org/show_bug.cgi?id=1823663) >>>>> >>>>> *WebKit*: Shipped/Shipping ( >>>>> https://bugs.webkit.org/show_bug.cgi?id=262878) >>>>> >>>>> *Web developers*: Positive (https://crbug.com/346473#c6) >>>>> >>>>> *Other signals*: >>>>> >>>>> WebView application risks >>>>> >>>>> Does this intent deprecate or change behavior of existing APIs, such >>>>> that it has potentially high risk for Android WebView-based applications? >>>>> >>>>> None >>>>> >>>>> >>>>> Debuggability >>>>> >>>>> None >>>>> >>>>> >>>>> Will this feature be supported on all six Blink platforms (Windows, >>>>> Mac, Linux, ChromeOS, Android, and Android WebView)?No >>>>> >>>>> Is this feature fully tested by web-platform-tests >>>>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> >>>>> ?Yes >>>>> >>>>> >>>>> https://wpt.fyi/results/uievents/mouse/mousemove_prevent_default_action.tentative.html?label=experimental&label=master&aligned >>>>> >>>>> >>>>> Flag name on chrome://flagsNone >>>>> >>>>> Finch feature nameMouseDragOnCancelledMouseMove >>>>> >>>>> Requires code in //chrome?False >>>>> >>>>> Tracking bughttps://crbug.com/346473 >>>>> >>>>> MeasurementWe have added the use-counter >>>>> kMouseDragOnCancelledMouseMove to track possible regressions in the wild. >>>>> >>>>> Sample links >>>>> https://codepen.io/mustaqahmed/full/wvNYGEP >>>>> >>>>> Estimated milestones >>>>> Shipping on desktop 122 >>>>> Shipping on Android 122 >>>>> Shipping on WebView 122 >>>>> >>>>> Anticipated spec changes >>>>> >>>>> Open questions about a feature may be a source of future web compat or >>>>> interop issues. Please list open issues (e.g. links to known github issues >>>>> in the project for the feature specification) whose resolution may >>>>> introduce web compat/interop risk (e.g., changing to naming or structure >>>>> of >>>>> the API in a non-backward-compatible way). >>>>> None. >>>>> >>>>> Link to entry on the Chrome Platform Status >>>>> https://chromestatus.com/feature/5145305056280576 >>>>> >>>>> This intent message was generated by Chrome Platform Status >>>>> <https://chromestatus.com/>. >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "blink-dev" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAB0cuO7reN%2B6Wb_N99jNm_aJY7fhhQ1ncCrh_J_%2BFCLdASm0eg%40mail.gmail.com >>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAB0cuO7reN%2B6Wb_N99jNm_aJY7fhhQ1ncCrh_J_%2BFCLdASm0eg%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFUtAY-UODWE9JKg6EbP3LLSUL8LoLtPqUCU7oQKb%3DSaVjf6Sw%40mail.gmail.com.
