After updating to Windows 10 Version 2004 [Windows automatic install update], Thunderbird buttons at top right of program work poorly. The button active area is extremely to the right of the button image and are not visible where active area is. If Thunderbird is not full screen, you cannot use them at all. You also have to discover this all by yourself as it seems the buttons do not work to minimize, maxamize, or close Thunderbird. Also, there seems to be a black bar partially over the buttons altogether which makes them very hard to access anyway. The program worked fine before Windows Update -- updated to Windows 10 Version 2004.