When SuperNova starts, a black and white image which resembles a QR code appears in the centre of the screen and may not go away until SuperNova closes.
This may occur if you have multiple displays set to "Duplicate". To workaround this issue, either set the displays to only show on one monitor, or press CTRL + ALT + DEL then press ESCAPE to remove the artefact.
Dolphin is investigating why this issue occurs and will update this article accordingly.
