Consider ARIA role for draggable resize handles

[ashfordneil]

Setting the resize property in CSS for an element (to a value other than none) creates a handle that can be used to resize the element. In applications that want to emulate that resize functionality, but require custom logic, often dedicated elements are added to the page to control resizing. These elements respond to click and drag events in a way that is similar to browser-native resize handles, but there is no clear documentation on how to make them either controllable via the keyboard, or accessible via a screen reader / other assistive technologies.

Keyboard control should be simple: these handles are just elements, and so like other form controls they could be focussed and then controlled using the arrow keys. I think the solution here would be to treat them like input sliders, only with two dimensions of movement.

Accessibility on these elements is a harder problem: I cannot find an ARIA role that would work for this resize handle. The closest things I could find would be the slider role or the proposed splitter role from #1348. However, neither of these handle two-dimensional resizing.

Is there an existing role / combination of roles that I've missed that should be used here, or is the solution that a new ARIA role would need to be created for resize handles?

[JAWS-test]

For resize separator is also suitable, but this does not solve your problem because with separator only in one direction the size can be adjusted

Authors MAY make a separator focusable to create a widget that both provides a visible boundary between two sections of content and enables the user to change the relative size of the sections by changing the position of the separator. A variable separator widget can be moved continuously within a range, whereas a fixed separator widget supports only two discrete positions. Typically, a fixed separator widget is used to toggle one of the sections between expanded and collapsed states.

[jnurthen]

sounds like another use case for #432

[jnurthen]

closing - please use #432 for this issue. If you disagree please reopen.