Thanks Original. What did you do in GIMP to fix it? I have Photoshop but I assume the process would be the same.
I still reckon there's a screenshot tool out there somewhere that can cope with parallax! If anyone knows of one, please post.
Well the issue here was not with the tool. Even if I scroll manually, this issue happens with last parallax image (it's edge shows up too soon).
I just injected some custom css to fix that, took a snipp with desktop screenshot tool and pasted that over original part in GIMP.