Do you have a situation in mind where a style benefits from having multiple different background shades available? Or are you thinking of this in regard to background images?
Yes, to be clear - I did mean images! I've updated the topic header to reflect this.
Thinking about Proxima's point here; maybe it would actually make more sense to implement a brightness-change option in the
player - that way, the level designer can set up whatever background colour/style/image they choose, and the player would be able to adjust its brightness to their liking*.
I wouldn't suggest being able to fade it all the way to black; the designer ought to have their level played as intended. However, the ability to adjust the brightness would be good, even if only to a limited number of settings.
I'd suggest that the settings reduce brightness
and contrast together to preserve the general detail of the background image.
I believe a plain black background should always be one of the options available to the level designer.
Maybe I'm misunderstanding what you've said, but I think this
is possible now: choose any theme with a black background (make sure the background image is set to "none"), and then you can use whichever elements you choose from any style to build your level (I feel like this isn't news to you, though, so I have probably misunderstood what you've said)!
The edge case I'd be concerned about here is orig_crystal - it specifically has a dark blue instead of black background because it contains pure black in the terrain and this has been abused in the past to create invisible terrain even without a customizable background
Maybe instead of a purely black background, it could be given #000001...?
Having said that, I like the #000030 background of the crystal theme: it's now my background colour of choice.
*
N.B. Just wanting to make it clear that I'm only suggesting that brightness can be changed, not the colour or the image itself