Disambiguation of path-based gesture versus dragging movement

[patrickhlauke]

This PR is a long-overdue disambiguation that removes the half-hearted retconning attempt to make pointer gestures apply to sliders at the time before we had dragging movements. (yes, this may mean that for 2.1, sliders MAY not be covered by pointer gestures anymore, but even with the additions we had, they weren't per se...so this doesn't actually change anything normatively in my mind, other than remove the weird points of overlap and confusion).

Pointer gestures

In understanding for pointer gestures:

• Remove the confusing "intermediate"/"midpoint" patch that was added mostly as a way to retcon/patch in applicability to certain looser swipe gestures and to some types of sliders, and instead explains in much simpler terms that while not strictly "path-based", the fact that the movement is only recognised when the path is "mostly" in a particular direction does make them count as path-based.
• Emphasise that for gestures, the end-point (and sometimes even the start-point) often don't actually matter so much as the direction (and potentially speed)
• Repurpose the "wiggly line from point 1 to point 2" to actually illustrate dragging movement, and move the two illustrations (straight line and wiggly line) to the section that tries to explain the difference between dragging and path-based gestures
• Use some consistency: start-point and end-point (not "start point", or "endpoint" etc, it was all a bit mix and match before)
• Adds a mention about gestures used to control UA/AT (similar to the mention present in the dragging movement understanding)
• Adds a very explicit mention that sliders are generally implemented using dragging movement, and are not path-based. Removes the very borderline example of a badly implemented slider
• Removes the artificial/stretched example of a kanban board that responds to swipes (which would be unusual) from the pointer gesture examples, rewords it to be an example for dragging movement
• Clarifies the (rare) instance of what happens when something (like a slider) involves both dragging and is path-based (that it may fail both SCs)
• Part of some confusion is how the word "slider" gets interpreted - some people say "slider" when they talk about a "content slider" or "carousel"; even one of the examples in pointer gestures fell into that ambiguity. This PR tries to disambiguate things a bit more and talks about "range slider" and "draggable carousels"
• Adds figures that show a range input slider and a draggable content carousel, to clarify the point
• Removes the paradoxical "input sliders are usually not path-based when used with mouse, but in some cases they're path-based when used with touchscreens" part. First of all, this seems to only happen in Android/Chrome (even Android/Firefox doesn't do this, and iOS doesn't). Secondly, this is a user agent choice, and authors can't be made responsible for it. Thirdly, we can't have these sorts of weird conditional "it's not path-based, EXCEPT on touch" statements...how is an author supposed to deal with that?
• In pointer gestures understanding, corrects mention of "swipes" for scrolling etc, and clarifies that these are on touch screen devices
• Remove the "Challenges for people with disabilities" section - after removing the inaccurate section about the difference between touchscreen and mouse operation for range sliders, the section only contains general points that are far better made in the intent section

Current version: https://www.w3.org/WAI/WCAG22/Understanding/pointer-gestures.html
Preview of the proposed changes: https://deploy-preview-4843--wcag2.netlify.app/understanding/pointer-gestures
Diff

Dragging movements

In understanding for dragging movements:

• Remove the mention of "intermediate points"
• Small language tweaks
• Same consistency change (start-point / end-point)
• Adds a variant example of a draggable news item carousel (mirroring the example of a carousel that can be flicked/swiped that exists in pointer gestures)
• Adds figures that show a range input slider and a draggable content carousel, to clarify the point

Current version: https://www.w3.org/WAI/WCAG22/Understanding/dragging-movements.html
Preview of the proposed changes: https://deploy-preview-4843--wcag2.netlify.app/understanding/dragging-movements
Diff

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Closes #3344
Closes #2394
Supersedes #3148
Closes #2684

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[patrickhlauke]

It's a draft PR for now, as I want to see if I can also cover/address other aspects such as #3148 #2116 and #2684

EDIT: worked some more on this PR, this now addresses these other issues as well

[detlevhfischer]

Looks very solid, great work, @patrickhlauke

[detlevhfischer]

Just some editorial comments - the substance is there.

[patrickhlauke]

Just some editorial comments - the substance is there.

thank you @detlevhfischer ... good to get some more of the cruft (most of it was existing text I think) out of those docs. I'll have a look through and make tweaks

[patrickhlauke]

Prompted by #4843 (comment) made one last (hopefully) big change:

Remove the "Challenges for people with disabilities" section - after removing the inaccurate section about the difference between touchscreen and mouse operation for range sliders, the section only contains general points that are far better made in the intent section

a53c434

[bruce-usab]

@detlevhfischer we did some editing on the TF call 4/3. Please take another look, to see if you are comfortable with the additional changes. (And please 👍 or remove your 👎 at top, commenting as you like.) We had consensus with folks on the call for keeping the “in some rare instances” example.

Already addressed