Hi, I clicked on the TB icon as usual to load messages but all that showed up was a blank screen with a blank rectangular box inside of it. My computer showed the messages were downloading, but all I could see was the usual apple in the menubar (I have a MacBook Air running Mojave) and "Thunderbird". I went through each option under "Thunderbird". Nothing would display, except that when I would click "hide TB", the white frame and any mention of TB would disappear. I tried to make you a screenshot, but the blank box inside the blank screen did not show. Ideas? Thanks.