open_centered causes visible relocation of window.

[hydra]

Despite dd4c544 which reads:

All of these changes now allow a window that is resize_to_fit to be initially hidden and show itself centered after being initially resized without any flashing or on-screen movement/resizing.

when I use open_centered the window appears in it's default position, then jumps to the center.

Example commit and app with the issue: hydra@aa27305