Adam,

I tried your demo and the trail marks disappear after I move the Image. I tried once again on my own and it still keeps the trailmarks - my version is also 5.2. Btw - when using firefox the zoom box isn't present in your demo.
But why does the trailmarks appear at all? Are there any way to get rid of them for good?

ps: The trail marks only appear when moving the image down or to the right. When moving up or to the left no trail marks are left and if the image passes over the old trail marks they are removed. This indicates that the calculated area when zoomed isn't correct. It seems as if it is of by one.