Figured out a work around; not sure if I had changed what I was doing to cause this, and changed it back, or if something that was working broke and now things have to be done another way. Anyway, issue seems to be when i have game set to "Windowed" mode, and set my window size to full screen. When window size is manually expanded to full screen (doesn't get the top margin, but I can live with that), flicker disappears.
Mysteries of Atys ... :-P
Mysteries of Atys ... :-P