To change the class directory, type in the path where you have put all your file viewers.
This directory is only used when the Pick button is pressed in the Actions Dialog. If all your viewer classes are in this directory, they can be identified easily. Viewer classes should be in this directory, or a subdirectory under it.
The path you type in does not have to be absolute. Directories such as '.' (current directory) and '..' (parent directory) are perfectly valid. If the directory cannot be found after you click OK, an error will be displayed.