Suggestion: Make Sextant-Affected maps 'glow'

Right now, I have to rely on a third-party website to make sure that where I'm putting my sextant is going to affect the map I'm aiming for. The range indicators are nice, but when it looks like it's barely in range it's hard to tell if it actually is or not.

What I'm suggesting is for all the affected maps to glow when cursoring over it with a sextant, much like jewel range in the passive tree when you cursor over it.