To explore the capabilities of the Shiny toolkit, we will build another complete graphical application. As the development of Shiny has been focused on the lower layer of graphical APIs, an application such as GoMail would involve the creation of many custom widgets. Instead, we will look at a more graphically-oriented application—an image viewer.
Building a user interface
Design
To get an idea of how the image viewer should look, we will make a rough design that we can follow. The online tool Balsamiq (balsamiq.com) is a good way to rapidly create wireframes that will suit this purpose. Take a look at the following export. It includes a navigation bar along the top, a directory listing on the left, and a full-size...
