Even though it has already been explained.
Say if you ever wanted for whatever reasons, to copy the text within whatever dialogue box, properties window, or any window for that matter, etc. virtualizing the window, allows one to select and copy text. There are several other examples I'm sure that would make it far clearer, but unfortunately, that's all that I have at the moment.

I only know of how to virtualize the window using JAWS though. If any of you know or are familiar with how to do the equivalent with any other screen readers, I'd appreciate your sharing this information if possible and thanks.