it`s reported in the very first post in this thread.
"the top bar of windows disappears and I can't open new windows"
I picked up on this thread because I had exactly the same issue, - the maximise/minimise and exit boxes were missing on ALL subsequent opened apps.
Not all apps have the option to open close with a file menu / tab so its a basic function surely?
and missing = broken.
TBH I won`t need support as I have no intention of showing it daylight again, - as I`ve already said, -it`s not really needed and the other apps do the job well (windows Blinds" etc.)
& I am a great believer in the saying "Once bitten, Twice shy".
(It`s already gone).
Thank you for your responses.