Add custom way to prevent forwarding.
An attempt to allow overlapping elements which forward events.

The issue is with mouseout and mouseover events. They are still not
computer properly, despite this more complicated implementation.
Revert "An attempt to allow overlapping elements which forward events."

This reverts commit 93b7ec0e3106034efd063d4614e2375d8e087a0d.
Use for events only highlight segments.

Highlight div itself is now again not absolutely positioned. This makes
events (like click or hover) really be triggered just at visible parts
of the highlight. Without a need for overlapping forwarding of events.
Cutout highlights when hovering.