I have been having this problem for years (no exaggeration; problems on Windows 7 and Windows 10 over many years and updates). Whenever I open a message, Thunderbird will attempt to open the message in a new tab, but the top of window, the menu bar, and any other tools disappear. I cannot even close Thunderbird, as there is no red X to close the window. I am forced to right-click the Thunderbird icon in the tool bar and close it (or just use alt+F4). When I reopen Thunderbird, the message is correctly in the new tab, and I don't have other tabular problems (at least until I open Thunderbird again). The same problem happens whenever I try to open a message after doing a search, except when I close and reopen Thunderbird, the message is not in a new tab, and my search results are also gone. I've attached two files. The first shows the Thunderbird application in error. There is no menu bar and no other interface tools. I am forced to close the window. The second shows how it looks after I reopen after closing. This is the correct behavior. Again, this has been happening for many years over many updates. Does anybody else have this problem on Windows? How can I fix it? Thanks.