Tip: Layer 3 backgrounds and tides disappear when you hit a message box, so plan your level around that. For example, you can add a sublevel without layer 3 at the start/midpoint, and include your message there.
Creates a "You hit this info box from below" flag. Also when it's set it becomes set to whatever the number of the message the info box was playing.
Creates a flag that when set, uses a new system for displaying messages. If you set this flag, message boxes will play from the CURRENT SUBLEVEL instead of the first level you enter on the overworld. It auto-detects invalid levels and if you are in one, it plays from the translevel number.
Automatically restores $13BF (translevel number) when a message is finished popping up. This is useful incase you want to temporarily change $13BF to another number so you can play multiple messages in a single sublevel. (For example by using custom sign blocks or NPC's.)
(If you change $13BF and don't restore it screen exits can get screwed up.)