It works and looks great except for one thing. The navigation buttons for the thumbnails hover over images, which is poor design. If you're at the very top or the very bottom, you really can't see the thumbnail well, and clicking is also problematic.
How can the code be modified so the nav buttons for thumbnails is NOT hovering over an image?
Only a change of the buttons themselves can fix this. Making them less wither so the underlying thumbnail be accessible. For this you need to change dmxPrevious and dmxNext classes in dmxgallery.css or overwrite them with !important statement in a style tag in the document that the gallery is placed in.