[css-ui-4] pointer-events should have a filtering capability #6280
Description
Once #4438 has the currently implemented version of pointer-events added to css-ui, we should take a look at the feature requests in https://wiki.mozilla.org/SVG:Pointer-events and our own issue list. One item on the Mozilla wiki is
Provide a way to filter which pointer events are intercepted by an element. For example, to specify that an element should intercept most pointer events, but not mouse wheel events. This would allow elements with fixed position to pass wheel events on to the elements below them.
There is also a request in #4499 to have a value that just stops events (instead of passing them through). I think it would be useful to combine these ideas and allow a CSS declaration that declares which events are handled, which are passed through, and which are stopped.
The particular case that led me to opening this issue is an overlay where we want it to respond to hover events, but have click events pass through to the element underneath.