Apparently that fix isn't 100%. It works exactly like my old Delphi does now, places the Dialog at the center of the screen and does not move the active form.
But this isn't so well either..
Testing recent Delphi 10.3, it would appear the old dialog option is ignored when testing with TopenDialog, it simply uses the OS Vista style. I don't know if this is a bug in Delphi or intentional ?
I've found that if I comment out the call to "Reposition", it works exactly like the Vista style and up Dialogs in windows, The dialog when showing follows the active form and I think that is more desirable and you still get the old style dialog showing as it should be.
Maybe a proper patch could be made to simply comment out the "Reposition" call... ?