I have the Dasung HD temporary, connected to High Sierra MBP and I can confirm that:
Mouse pointer makes things dither around it.
Toolbars dithers too.
Opening the Updates window, toolbar dithers only in the middle around the icons, but rest of it not. Regardless of the mouse pointer.
Now come some other interesting observations, I'm opening "sky/clouds" picture and it dithers like crazy in all browsers, Chrome, Safari, Waterfront however if I take screen shot of it, that picture it dithers way less! But the colors are supposed to be same, or the picture has lower quality? :S
Another observations is that the Dasung disconnects every time I open new tab in all browsers.
If I start flux everything dithers, however there is no way to have the Dasung stay connected with Flux <4K, as soon the slide bar passes it, Dasung disconnects and won't connect, restart does not help either, must stop flux.
Wait for it, now plugging my recent good solution, Chromebook, same web image, no dither at all, mouse pointer, no dither too!! Everything is static! It does not disconnect whatever I do!!
PS. I do not use the Dasung drivers, as they seem do not support High Sierra and the whole laptop becomes crap slow.