Re: [csswg-drafts] [css-overscroll] overscroll-behavior should not prevent visual viewport "panning" (#12919)

The CSS Working Group just discussed `[css-overscroll] overscroll-behavior should not prevent visual viewport "panning"`, and agreed to the following:

* `RESOLVED: existing overscroll-behavior values that prevent scroll propagation don't prevent visual viewport panning`

<details><summary>The full IRC log of that discussion</summary>
&lt;emilio> vmpstr: if you have a scroller with `overscroll-behavior: contain` and you pinch-zoom<br>
&lt;emilio> ... then you can't pan that visual viewport around if your mouse is in there<br>
&lt;emilio> q+<br>
&lt;emilio> ... I understand why<br>
&lt;emilio> ... but I find it unexpected<br>
&lt;emilio> ... the panning part seems like a very strange and unexpected limitation<br>
&lt;flackr> +1<br>
&lt;emilio> ... I'd like to change that<br>
&lt;fantasai> scribe+<br>
&lt;Rossen> ack emilio<br>
&lt;fantasai> emilio: Are people using it to implement their own panning behavior?<br>
&lt;fantasai> emilio: e.g. Google Maps, when you pinch-zoom, the app needs to do something, handle its own gestures<br>
&lt;fantasai> emilio: I could imagine them using this instead of event listeners and defaulting<br>
&lt;fantasai> flackr: If an app is implementing pinch-zoom, they shouldn't allow pinch-zoom into visual viewport<br>
&lt;fantasai> emilio: What if it's embedded? You only want to constrain pinch-zoom in that area.<br>
&lt;emilio> vmpstr: from my perspective, if there are valid use cases for that we should enable them. But I think the default behavior shouldn't be there<br>
&lt;fantasai> vmpstr: If valid use cases for that, we should enable them, but default behavior of "I don't want to change my scroll, side-effect is that you can't pan around pinch-zoomed area" is not great<br>
&lt;fantasai> emilio: I agree with that in theory, but a bit worried about ppl abusing that already, but we can try<br>
&lt;fantasai> emilio: There's a good use case to prevent pinch-zooming in a particular scroller. Embedded map use case, for example. Seems pretty reasonable to specify that with CSS, so that you [missed] and deal with pinch-zoom yourself.<br>
&lt;fantasai> emilio: But we could introduce a new syntax for that.<br>
&lt;fantasai> emilio: Just worried about other pages relying on it.<br>
&lt;fantasai> flackr: There's a touch-action property that you can use to prevent pinch-zooming.<br>
&lt;fantasai> flackr: Don't think we have equivalent for mouse zoom.<br>
&lt;fantasai> flackr: Invoking browser zoom is going to be a weird situation.<br>
&lt;fantasai> flackr: In any case overscroll-behavior is not how you would avoid pinch-zoom panning.<br>
&lt;fantasai> vmpstr: I pinch-zoom a lot, it's very disturbing when I can't pan around that<br>
&lt;smfr> q+<br>
&lt;fantasai> vmpstr: If the site has some intentional desire here, they should indicate explicitly using a special property or something.<br>
&lt;Rossen> ack smfr<br>
&lt;emilio> scribe+<br>
&lt;emilio> smfr: I support the proposal, I think gmaps shows a message (hold the command key or so) to zoom the map<br>
&lt;emilio> PROPOSED: existing overscroll-behavior values that prevent scroll propagation don't prevent visual viewport panning<br>
&lt;flackr> +1<br>
&lt;emilio> RESOLVED: existing overscroll-behavior values that prevent scroll propagation don't prevent visual viewport panning<br>
</details>


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Received on Wednesday, 4 March 2026 17:27:12 UTC