78.4.1 (32-bit): When I move my mouse over an unread message (shown in bold text) in the message list panel, it disappears! If I move the mouse over a message that has been read, nothing changes. Once I click on an unread message, the message body appears in the viewing panel even though there is no visible text where I click. This behavior is new. No crash reports since 3/3/2020.

Any ideas? The last few updates have changed the appearance of the GUI and introduced unwanted behavior like increased line spacing between messages. Is this some form of improvement that I'm not understanding correctly?