Description
In Issue #7647 it was resolved to support pseudo-classes on pseudo-highlights. The canonical use case being hover on custom highlights.
How should we define the active region for detecting the pseudo-class trigger state, when it may be that only a portion of the element is highlighted by the pseudo-highlight? My initial proposal is that the highlighted area should trigger the pseudo state.
For example, if you have code highlighting turned on for a single pre, such that different ranges are highlighted with different highlights, a pre::highlight(blah):hover would only trigger when that specific highlight area was hovered.
If you have #tooltip:hover and ::selection::hover and you selected part of the tooltip, then hovered, the selection would match ::selection::hover and the rest of the element would match #tooltip:hover.
Thought needs to go into how this would be implemented.