Previously, blackout was bugged and didn't work properly. One of these bugs was that text boxes didn't fully fade out when they were closed during a blackout. The easiest way to see this is to turn screen effects off, then play the main game intro cutscene.
However, since #923 was merged, this is no longer the case.
There are custom levels that rely on this effect to make certain things look good, such as teleporter menus made out of text boxes and player movement. So, this should be fixed.
Previously, blackout was bugged and didn't work properly. One of these bugs was that text boxes didn't fully fade out when they were closed during a blackout. The easiest way to see this is to turn screen effects off, then play the main game intro cutscene.
However, since #923 was merged, this is no longer the case.
There are custom levels that rely on this effect to make certain things look good, such as teleporter menus made out of text boxes and player movement. So, this should be fixed.