[css-overflow][css21] overflow:hidden SHOULD or MUST not be scrollable?

[frivoal]

Via language that was carried over from css2, overflow: hidden is specified in css-overflow as (emphasis mine):

This value indicates that the content is clipped and that no scrolling user interface should be provided by the UA to view the content outside the clipping region. However, the content may still be scrolled programatically, for example using the mechanisms defined in [CSSOM-VIEW].

I do not believe that this should is intentional, so we ought to replace it with must. overflow: hidden isn't meant to be scrollable except via script. Or is it?

I'm asking because iOS has a bug where it is scrollable in some corner cases. But if we have should rather than must, then maybe it is not a bug.

References:

• demo of the bug
• webkit bug
• proposed test case

[frivoal]

Agenda+, because this ought to be easy and then we can move on.

[smfr]

I don't think the iOS behavior was intentional. I'm OK with making this a MUST.

[frivoal]

Spec updated in to match in commit af1704d