I found few issues related to setting Region's TintLuminance.
Most simple way to observe the problem is this:
1. Select Region in the editor and set UseColorTint = true with some TintLuminance value.
2. Save room, then reopen room. UseColorTint will be = false, and LightLevel is set to some
seemingly arbitrary value instead.
EDIT: Hmm... I just realized this happens if you don't set TintSaturation, when it is 0, tint becomes cancelled. I am not sure this is how it worked before.
Actual issues:
1. LightLevel/TintLuminance value breaks when you reopen room. This occurs when you open room in the editor, because if you just set it once and save, in game they seem to work properly in general.
2. Glitched detection of whether light level or tint is set for the region (so far in Editor, I think engine works well in this aspect, but this needs more testing).
3. There is no Region.TintLuminance property in the script, to complement other readonly Tint* properties.
4. Region.LightLevel property returns meaningless values if colored tint is set (it should probably return default light level - 0).
5. Region.TintSaturation property returns light level instead of actual saturation, both in Light and Tint modes (this is remains of older implementation that I did not change when adding TintLuminance in this version).
EDIT:
6. In previous versions when you set ColourTint on, Saturation is 50 by default, but now it is 0 by default... which makes it easy to forget set it to something.
EDIT2:
Supposedly fixed version for test:
http://teamcity.bigbluecup.org/repository/download/AdventureGameStudio_Release/13066:id/AGS-3.4.0-RC1.zip