Allow each highlighter color to have its own opacity
The opacity setting for highlighting seems to apply to universally across all colors. I think a better approach would be to allow a different opacity setting for each color.
In my experience, there is no single opacity setting that provides decent readability for black on white text where the color of the highlighter is important. As a result, workflow suffers when having to adjust opacities after switching among colors, something that happens frequently when commenting my documents.