I am so tired of the "lighting needs to be rebuilt" message on my screen:
I am constantly moving stuff and the lighting on a couple of my boards can take upwards to an hour. Even on my maingear monster.
I need vid caps from my game to build a trailer and these messages have to go.
Fortunately they are easy to remove.
In UDKEngine.ini adjust this setting:
restart UDK and voila, no more nags.
This is for UDK 3. I'm not sure if this applies to UE4.