When creating a user-interface in IDL, you have several choices. In order of increasing complexity, you can use any of the following:

• IDL command-line interface: Using the IDL command line as a non-graphical user interface to display graphics visualizations, or data in the IDL output log.
• Existing iTool Interface: Using an existing iTool provides quick data display and manipulation capabilities for image, plot, surface, volume and map data.
• Custom Widget Interface: Using widgets offers complete control over user interface design. However, in a traditional widget application, you must code all underlying functionality. There is an option of creating a hybrid widget-iTool application, but this requires additional programming expertise.
• Custom iTool: Using a custom iTool interface allows you to expand on the capabilities of the standard iTool design, and configure the appearance of the tool. This requires the most programming expertise of the three options. It is likely that one of the other two options will meet the needs of the majority of the applications, but this level of customization is available for those who require it.