in 5.9.0 -> ok
in 5.11.3 ->not ok

Attached test application

• QSettings used for saving position
• messagebox for showing coordinates in open and close

Steps:

1) click in menu on "Test->showMyDlg" to open the dialog.

2) Close the Dialog using the cross in top right corner of the dialog.

3) repeat step 1-2 to watch the dialog moving down...

If do NOT use the cross at the top right corner of the window to close
the dialog but close the dialog using the 2 buttons (Close or Reject)
the moving does not happen.