Qt, how does Synchronize move two windows?

recently writing a player, now there are two window classes, one is QMainWindow class: SImplePlayer, is my video window; the other is playlist, QDialog class, I want to drag the video window, that is, my SimplePlayer window, my playlist can move, what should I do?

move the window on the left and move the window on the right. What should I do?

Qt
Dec.12,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b382da-4d78f.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b382da-4d78f.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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