Whole message lines disappear in the Thunderbird 38.8.0 mail client on Lubuntu 16.04.
The Alt+Tab switcher shows icons, but shows no text. So the problem is likely not specifically with Thunderbird, though Thunderbird is the only app that exhibits the problem.
It looks like this (I've whited out most of the columns for privacy, but you can see the issue in terms of lines that have no text):
Closing Thunderbird and reopening resolves the problem until the next time
the computer is put to sleep and wakes up again. Only other programs running are
sublime-text-3. The problem does not occur 100% of the time.
Running from the command line did not generate any useful debugging information.