If a content element receives a click, touch or drag event, the event bubbles up through the content element's place in the DOM, and the region that displays the content (and its parents) never hear about it.
*** Bug 15679 has been marked as a duplicate of this bug. ***
An elementsFromPoint() method has been added to CSSOM-view:
This will in most cases allow code to determine which fragment container has been clicked. It will not fix CSS hover styling.
An additional 'paint-order' value for pointer-events is proposed for a future level of CSS UI:
This would optionally allow user events to pass through the stack of elements under the event coordinates. This would the issue for both click events and CSS hover styling in fragment containers.