The code I've been using is:
1.System: 1Start of layout
TextManipulatorSet string to TexttoDisplay 0 .Text
2.displayText: 27 Text is TextManipulator 0 .GetString (case: No)
displayTextSet text to TextManipulator 0 .GetLeft(displayText 1 .Value('currentdisplay'))
displayTextAdd 1 to 'currentdisplay'
//IE: Are the 2 strings not equal?
3.Button: 18 On Button clicked
TexttoDisplaySet text to "This is typing!"
displayTextSet 'currentdisplay' to 0
TextManipulatorSet string to TexttoDisplay 0 .Text
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This is the important part here:
"TextManipulator.GetLeft(displayText.Value('currentdisplay'))"
it uses 2 strings: 1 to hold the text, and the other to display it.