Undo while prompt text box is focused

[JTJutajoh]

Currently, when the prompt text box is focused and Ctrl+Z is pressed, it works like pressing Ctrl+Z in photoshop itself does, flipflops between undo and redo. However, pressing Ctrl+Shift+Z does not behave the same way that it does in photoshop itself, and still just flipflops between undo/redo rather than stepping back in an undo history.

I think this is not ideal behavior and there are two possibilities for how it should behave instead:

1. Ctrl+Shift+Z should step back in undo history like it does in photoshop itself. I understand this may be a big ask if there isn't already an implementation of an undo history for prompt entry.
2. The text box should ignore Ctrl+Z and Ctrl+Shift+Z keyboard shortcuts. When the user uses those shortcuts while the text box is in focus, photoshop just behaves as normal and the text box is unchanged.