Lyrics mode: text toolbar flickers when moving between syllables
Win 10, MS 184.108.40.20666, revision: 7684abe
This may be a Windows 10 specific issue. It wasn't present in MS 2.3.2, and probably not in previous versions of MS 3 either.
In lyrics mode, when you use any command to move the cursor to the next or previous syllable, a black rectangle flickers on and off over the first four icons of the text toolbar at the bottom of the screen.