We now have a list of requirements for our mapping application, together with the geospatial data we want to display. Before we start coding, however, it's a good idea to step back and think about our application's user interface.

Our application will have one main window, which we will call Landmark Explorer. To make it easy to use, we'll display a map canvas along with a simple toolbar. Our basic window layout will look like the following:

Along with the main window, our Lex application will have a menu bar with the following menus:

The toolbar will make it easy for new users to work with Lex by pointing and clicking on the toolbar icons, while experienced users can make use of the extensive keyboard shortcuts to access the program's features.

With this design in mind, let's start coding.