Reflow: add more techniques and examples

[scottaohara]

A follow-on issue to #4055. There were many ideas for additional examples and techniques. But, adding all of those would have extended the time to get the updated understanding doc in front of the working group for discussion.

The following are ideas we should continue to consider / create to further improve the reflow understanding document.

• more examples of expectations of where two-dimensional layout could be used in tandem to other page content which 'should' be able to collapse into a single column.
  • an interface where a sidebar navigation remains persistent, but the remainder of the content should be able to fit within a 320px area.
  • an interface where a chat widget is present in one column, and automated prompts which update in real time to the content of the chat
• examples of UI that has exceptions to Reflow - but where an accessible alternative should still be provided
  • an editable canvas for presentations or website building or a rich text document that needs to be presented as a particular width, but an alternative preview/presentation exists which could then work for reflow.
• examples of where text truncates within form controls (text fields, listbox popups)
• other examples of text with specific formatting requirements (e.g., poetry / potentially other instances of preformatted text)
• examples of how other SCs fail when sticky headers/footers or popups make it difficult to use the underlying page, or re: the popup example, might be positioned off screen.

[mbgower]

I'd add to this list the idea that not all versions of a page need to meet Reflow. If there is another 'view' that provides equivalent function the SC can be met.
Thinking of the variations in MS Word's Comments/Review presentation, one can basically stack the main content and comments views, so that there is no horizontal scrolling required to keep the main and comment in view. I would argue that since the vertically stacked view exists, the SC is met, regardless of whether the side-by-side view passes.

[detlevhfischer]

One area that could also possibly be covered in 1.4.10 is breadcrumb behaviour in narrow viewports. The issue that was just raised by a German tester. He lists three different common approaches for dealing with breadcrumb paths that are too long to fit in the viewport, which are all problematic and may or may not be considered a 1.4.10 pass (sometimes depending on other SCs like 2.5.1 being met (or not met):

1. The breadcrumb is swipeable
While this seems a clear violation of 1.4.10 Reflow, it is has the advantage of saving 3-4 lines of text for long paths that would push down content.
2. The breadrumb is truncated with elipses (...)
Here, the breadcrumb is partially hidden for long paths. After clicking on the ellipses dots, the breadcrumb is fully displayed.
Users may not expect the popup mechanism. In addition, the main function of the breadcrumb (showing the hierarchy) is lost (unless the mechanism is discovered).
3. The breadcrumb is shortened
This is a common variant. For longer paths, the breadcrumb is hidden and only a link to the parent page remains.