0 Off The entire viewport is always rendered.1UnionAll dirty regions are grouped into the smallest possible rectangle. This is typically the fastest mode for slower GPUs due to only making one pass.
2 Cost reductionEach dirty region is presented separately, in as many passes as there are regions.
3 Whole ScreenThe entire screen is rendered if there are any dirty regions. This, combined with nofliptimeout is a safe default for drivers that clear buffer contents (manifests as blinking or vibrating images). Default
So, what's your point exactly? What issue do you have with the interface? Is it too slow? Too fast? Is it flickering? Do the smurfs appear and start dancing all over the interface, making all sorts of dirty regions?
As i understand from the article:
The dirty regions setting affects how the interface is rendered. This effects the load on the CPU/GPU and therefore can have an effect (good, bad, not percebtible by the naked eye or anything in between). So it likely most people won't even see much difference when altering these settings, most do not even see the stutter which occurs when using external subtitles!