After 3 hours of experimenting with it, I have to say that I got some interesting results, but not what I wanted
Still trying, cause I think this would be a great effect

But I don't think I can get it right
Just 2 remarks (correct me if I'm wrong as this could be):
Wouldn't it be necessary to increase the message length on each "loop"?
In your current code [letter=mid(msgtobedisp,i,1)], in each round there would be only 1 letter displayed I think.
Somehow, multiple timed events don't seem to work. I've also tried it with a specific script to display a certain word in a certain textbox, but after the second letter it stopped for some reason
Have you already tried it with a specific code, too? Have you been able to create a multiple timed event that works for the contents of a textbox?