Hello,
I tried Ubuntu mate 18.04 on my laptop, an Acer Aspire 5733 with an Intel HD Graphics card. When I try to have a double window, or when I pass Youtube in full screen, I have a problem, the window goes well to the bottom, but not what is inside. I have to restart the window several times for it to work. I do not have this concern with other offices. Where can this come from ?