Rejection reason: after long discussions, it was decided that this is an unwanted feature (not even as optional feature!)
I humbly request an UI improvement regarding lightning. I often have difficulty knowing whether a tile is considered illuminated (use day vision to calculate visibility) or not illuminated (use night vision to calculate visibility). Some sort of overlay that can be toggeled would be nice, like the night vision indicator. An easier and additional way to display this information would be to change the color of the unit facing indicator arrow (when pressing alt). The arrow can be darkened to indicate a unit is standing in darkness.
I would actually darken half of the arrow to have an obvious distinction to the normal arrow.