I select part of an image, copy, and paste it elsewhere in the same image (png):
#1. the quality is not as sharp as originally - it's quite blurry actually.
#2. I do notice that, if I click and drag over an area including the pasted bit, that it momentarily shows as sharp as the original.
#3. if I view the image elsewhere (viewer/photoshop), the pasted part is not sharp
#2 above makes me think that the quality of the paste could possibly be made as good as the original image (?)
There is unusual behaviour when cropping the image cuts part of the pasted clip - *all* of the pasted clip continues to show in SC. The thumbnail correctly shows this pasted part cropped, and it also shows correctly in other viewers I tried.
Which seems okay, but if something is being cropped e.g. for privacy reasons, I presume that if I can see it in SC, then others would be able to see it in SC or possibly elsewhere (?)