Michael,

I was wrong, this issue is not fixed in nov19 beta at all. Fortunately I've managed to isolate the problem. I can totally confirm something in SidePane.htm is causing the flickering. Couple of days ago I've done some modifications to SidePane.htm and that's why my flickering issue was resolved! New beta was out that time, so I suspected you fixed it. I still can't figure out which particular line causes the flickering though.