I've downloaded the PDF for the paper linked on the page (http://faculty.washington.edu/wobbrock/pubs/uist-07.01.pdf http://faculty.washington.edu/wobbrock/pubs

I've downloaded the PDF for the paper linked on the page (http://faculty.washington.edu/wobbrock/pubs/uist-07.01.pdf http://faculty.washington.edu/wobbrock/pubs/uist-07.01.pdf) and some of the images are not showing. Is this a problem with OS X Preview.app or a general problem?