Does all systems support gamma control?

[StillInThe90s]

I realized that all my backgrounds and sprites were made on a pretty bright screen, which might leave some players "in the dark" so to speak.
It looks like a gamma slider might be a quick fix but only if people can use it (obviously).
So, when the manual says:

"..whether the player's PC supports changing the screen's gamma control settings"

..does this mean that it won't work in window mode -period, or will it only work on some machines?
If so: are non-gamma-setting -systems common?

[Ghost]

Gamma will only work in fullscreen mode, as soon as someone has to run your game windowed, he can't use AGS gamma and will have to adjust his monitor. There's no way around that.
In my experience each and every (recent) computer allows you to either tweak your monitor settings directly and/or gives acess to the graphics card's panel; so:
Yes, people can change their setting to play your game.
NO, they won't like it

_
edit:
I ran into a similar situation with my very first game (what was black on my monitor was barely 60% grey on a well adjusted one). The thing is, just tweaking brightness will result in colours looking all wrong; personally I'd say you're better of recreating the images, and reimport them. Might be a lot of work, but it's usually worth it.

[Cassiebsg]

Probably silly question, but can't you just load your BGs on your paint program, adjust the gamma and then re-import them into the game?

[Khris]

Silly indeed, since people have their monitors set to different levels of brightness, which is what causes this problem in the first place

[StillInThe90s]

Alans last Draconian build seems to be supporting windowed gamma control.
Could this be an option?

EDIT: I tried compiling with draconian 7 and it looks promising. Any known issues with this build?