Ok, Thanks 
I think things like partly rubbish or black part at bottom or right and/or repeating desktops are probably caused by still missing ‘link’ programming somewhere. This should not happen (or the best shot for you to not have this) is having the desktop at the same settings the icons screen is shown at boot time.
I would expect analog screens to not have this anymore if they are the only connected screen to a card since all programming needed should be in place (in the V4 driver: git still misses a piece for that being panelfitter setup).