Designer is the program that is used to create a user interface for the Orbiter. Designer has not yet been re-written for LinuxMCE 2. While functional, it is not terribly user friendly, and it only runs on Windows. The User's Manual explains how to use it. Eventually an entirely new cross-platform Designer will be written. However, since it is still useable, this has been considered a lower priority.
Designer is very poorly written, and we do not recommend any developer puts much effort into this code. It needs be completely re-written from scratch. What makes matters worse is that it was originally written using our own .NET data access classes, similar to our sql2cpp. However these classes only worked with MS SQL Server as a back-end. For Version 2, we are using the open source MySql database. The data access classes were crudely hacked to work with MySql's ODBC connector and are not easily maintainable.
Since re-writting Designer is a pretty big task and the current version is somehow useable, we have considered this a lower priority. The database schema is not likely to change much when the new Designer is written, so any user interfaces developed now should be useable with the new Designer. There is no Programmer's Guide for this version of Designer.