Typewriter Mode: Adding Overscrolling to the Text View
Typewriter modes depend on the feature that you can scroll farther up and down than usual. You need extra whitespace, most of the time in both directions. Let’s start with “overscrolling” to understand what we need. Regular text views show additional bottom whitespace only until you fill it with text. Take TextEdit, for example. You can start to type at the topmost edge of the text view and the rest of the window is blank.