Comment 5 for bug 1746146

If you look at the right edge of the image, opposite to the "C", the rest of the "C" as it fades out can be seen - but the dark area is to the left, not the right.

This appears to indicate that the columns of pixels that are transferred are brought over in reversed order (mirrored).

(If the chopped-off gap-leading-to-"C" were not reversed, the dark area would be on the right fading to the left as it leads from the "C" into the gap).

I hope that I have described clearly enough, what I am seeing...