[Feature]: Mark commented highlights

[mzechmeister]

Is the feature relevant to the Firefox PDF Viewer?

Yes

Feature description

Highlighted text passages can be annotated with comments. The comments are displayed when hovering.

A little sign could indicate whether the highlighted passage has a comment at all, so that hovering is not nessary.

Other PDF viewers

Acrobat has this feature:

Note the little speech bubble above "highlighting".