A selectable image viewer

In our final selectable example, we're going to make a basic image viewer. Images can be chosen for viewing by selecting the appropriate thumbnail. Although this sounds like a relatively easy achievement, in addition to the actual mechanics of displaying the selected image, we'll also need to consider how to handle multiple selections. The following screenshot shows an example of what we'll end up with:

The images used in this example are provided in the code download because they need to be the correct size for this example to look right. There should be eight of both the large and thumbnail versions of each image, and the sizes of each are 110 by 110 pixels for the thumbnails and 400 by 400 pixels for the large versions.

Create a new directory called selectable within our img directory, then create a new folder called image-selector inside this. Next create two new folders inside the previous one called large and thumbs. You should place the thumbnail images from...