Window resources are not released - window management block

Under Linux x11, the KDE win system is used, and the stress test program is executed for more than 24 hours, and the windows are constantly displayed and hidden, and finally the entire system is blocked.

This stress test program simulates the operation of kwin's tabbox. It was found that the resources were not released quickly when the window was destroyed, and the resources were not released until the next time it was displayed.