Merged requested to merge ngraham/spectacle:darker-rectangular-region-overlay into master
The effect is quite subtle, to the point of being difficult to see. Darkening (for the default dark overlay effect) or lightening (for the optional light overlay effect can make the effect easier to understand.
No screenshots for the light version, which is changes less and seen less frequently since it's a non-default option. I'd like to look into removing the option and instead automatically using it when the system has a dark theme, but that's for later.