I have a solution ??
Thickbox, Highslide, and all those fantastic js viewers out there need the links to be in the page, just hidden. If you look at the examples of highslide for example that shows one thumbnail for a popup that shows a gallery of images, they are just setting the display of all the other thumbnail links to display:none. So everything is still there which is why we can’t have NextGen only show one thumbnail.
Ideally NextGen could create a div around all the thumbnails except for the first one and give us the option to display them or not. But since that’s not the case I have a different solution that I’m pretty sure works in every browser.
Every NextGen gallery is enclosed by a div of class “ngg-galleryoverview” we will set the height and width of this div to match the height and width of one thumbnail and then set the overflow to hidden (We will also add position:relative for IE). So in wp-content/plugins/nextgen-gallery/css/ edit “nggallery.css” and add this at the bottom:
.ngg-galleryoverview {
overflow: hidden;
position: relative;
height: 97px;
width: 122px;
}
The height and width will depend on your thumbnail size. 122 x 97 works for the default ( 100 x 75 ).
One caveat is that let’s say you want your gallery thumbnail to be something large, your site will load that size thumbnail for every image in your gallery and take forever to load. But if you’re sticking with a reasonably small thumb, I think it will be fine.
It’s not the best solution. But it will work.