Hi there!
I guess now I finally understood exactly what you mean. You don't want for it to just show new messages, you want to work like a message log, with a similar function as the Scroll Text window, right?
So the player can open the window, and scroll to see all the messages?
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About the letter sounds, I will give it here a try because it's something I also want. I can confirm I will make it work with letter sounds.
But the other request I will have to take a look at it first and see if is suitable to put this feature on this plugin.