External Programs allows to define a list of applications. These applications can be started by using the context menu of the browse window. On starting, the application gets the names of the selected files as parameter.
Additionally you can use the external programs in combination with the active document or active layer by using the Filter menu.
In order to create a new entry you have to set the path to the application using Browse... first. After that you can create the entry with the "+" button. The list allow you to modify the program name anytime.