My program doesn't have bugs. It just develops random features.

From Unreal Wiki, The Unreal Engine Documentation Site

"RGB(127,127,127) is transparent" - I just noticed this and this sentence is wrong. The actual value for modulated *full transparency* is RGB(128,128,128), not 127. A simple test like making 2 decals with 127 and 128 respectively as background, and then keep adding them to a wall will show that the 127 one will eventually show the background as it darkens, while the 128 keeps transparent.