How can I lock the screen when using Presentation Mode?

Background

In GoodNotes 4's presentation mode, you were able to lock a part of the screen to make that part visible on the external screen only while being able to edit the rest of the page without distracting your audience.

Solution in GoodNotes 5

GoodNotes 5 also allows you to solve this problem, even though it works a bit differently. Here's how:

1. Open the same document twice in two windows.
2. In the GoodNotes window that you will not want the audience to see, tap the Share button in either window and make sure GoodNotes is set to "Mirror Presenter Page".
3. In the other window, which will be visible to your audience, tap Share and choose "Present from This Window."

You can operate these two windows independently from each other. You can adjust what your audience sees by zooming in the presenting window while you still see the entire page in the hidden window. This allows you to flip to other pages of the same document to look something up or to continue writing on the next page while your audience still sees the presenting window.