Robin, it might be helpful if you'd tell us what we're looking at...
Is it a screen grab from an image you're working on at lower than 100% zoom?
It only happens when I am moving stuff.
If you're talking about the resampling for zoomed displays being different when moving document windows around (vs. when they're stationary and you're doing edits), that's because OpenGL drawing is temporarily turned off for the display of the image while you're moving its window around.
Zoom rendering is different (smoother, higher quality) in OpenGL than non-OpenGL operation.
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