Email view window is blank when an email is selected, menu items are also blank until the cursor is passed over them.
The e-mail view window is blank when an email is selected, this also occurs when the email is opened in a new tab. Taking the cursor and highlighting the text will reveal it. When typing text a new message, text will often disappear and reappear. Menu items and other parts of the UI are also blank until the cursor is passed over them. I'm currently running version Thunderbird 38.5.1, this issue also occurred in version 38.5.0 but not in earlier versions. Safe Mode corrects this but you loose Lightning calendar functionality.
Alle Antworten (3)
What other add-ons and themes do you have installed?
Other than Lightning I only have the TT DeepDark theme installed. All plug-ins like Adobe, Java, Shockwave, etc are disabled. Disabling the TT DeepDark Theme doesn't correct the issue. The issues are more or less constant though I didn't notice the issue when working remotely for an hour or so last weekend but it's back now that I'm at the office. I use 2 monitors via DisplayLink at my office. This configuration worked normally with previous versions of Thunderbird so there may be a conflict somewhere.
There "might" be a driver conflict. But I use two monitors all the time. It has it's frustrations. But it works.
On the toolbar 
> Options > advanced >General and toggle the use hardware acceleration. Most folk do best with it off. But with weird graphics glitches no setting is necessarily better. Having it on does not make Thunderbird run faster.
While testing, revert to the base theme as well. All themes periodically suffer from graphics issues when a new version is released. Sometimes is a new object that is no in the themes graphics. Sometime the way graphics are drawn changes. Usually the Theme authors are on top of it very early on. But for testing the base theme is a necessity to separate the issues.