Sorry, I cannot get anything out of these pictures.
A quick research shows me that by far not all dialogues appear in the middle of the main window.
File>Options: fixed position
File>Playlist: fixed position
Search box tag source: fixed position
File operation dialogues: fixed position
Track numbering assistant: fixed position
Actions (quick) dialogue: fixed position
DB cleanup: fixed postion
Message boxes: keep last position
Convert dialogues: keep last position
Actions>Actions: keeps last position
File>Export: keep last position
I don't know whether I got all of them, probably not
So I would say: depending on your favourite functions, you already have that feature