Can be targeted by pointer events

An element can be targeted by pointer events when all the following conditions are true:

• the element is has a semantic role that inherits from widget; and
• the element is focusable; and
• the element computed value of the pointer-events CSS property is auto.

Background

This definition tries to capture which HTML elements can actually react to pointer events. It is not possible to have an exact definition of these for two main reasons:

• Sometimes, the element that handles the event is not the element that appears to react to it, but an ancestor (or descendant) capturing the event during propagation or bubbling. In the most extreme case, the body element of a page could be the only one with an event handler, acting differently depending on where the event actually occurred. In such a case, a button would be perceived by users as something that can be targeted by a pointer event, while technically it is the body element which is targeted.
• It is not possible to query the list of event listeners on a given element. Some User Agents offer a way to monitor events fired at a given element, but none offer a way to query for event listeners. Additionally, an event listener might ultimately do nothing and thus, for users, the corresponding element wouldn't look like it can be targeted by pointer events (since it effectively wouldn't react to them).

As a consequence, this definition has these two known limitations:

• Not all HTML elements that can actually be targeted by a pointer event match this definition. For example, an author may build custom buttons without giving them an appropriate role or making them focusable; or content overflowing the border box of an element is clickable, but that element might not match the definition if the border box is off-screen. Elements that can actually be targeted by pointer events but do not match this definition likely fail either Success Criterion 4.1.2 Name, Role, Value or Success Criterion 2.1.1 Keyboard.
• Not all HTML elements that match this definition can actually be targeted by a pointer event. For example, when the actual clickable area does not cover the full border box and is entirely covered by other elements, or when the element has an event handler that does nothing. Elements that match this definition but cannot actually be targeted by pointer events likely fail Success Criterion 2.5.6 Concurrent Input Mechanisms.