Rendering <select> as a listbox is a one-line widget that opens a popup on iOS and Android

[zcorpan]

See #3410 (comment)

I suppose there's a good reason for this in terms of usability -- it may be hard to select options on a touchscreen without sufficient spacing, and taking up more space for an inline widget might be less web-compatible compared to showing a one-line widget.

On even smaller screens like a watch this approach also makes sense.

HTML doesn't currently allow it in the rendering section, however. What should the spec say? Allow either inline listbox or a one-line widget that opens a popup?

cc @whatwg/forms @mfreed7