The 3Delight Preferences Dialog
These screenshots have to be taken again with less to be redone with less drop shadow (while the dialog is not 'raised'). Also, the 'Viewing' one will have all only the Render View parameter. I think it would be better to simply put everything in same window/tab with a separator (not even sure is necessary.) TWBTW: spacing between items on Engine side is not the standard spacing (too close together).
Render Engine tab of the 3Delight Preferences.
Viewing Apps tab of the 3Delight Preferences.
The Render View preference is for selecting the window (and application) in which image layers are displayed during rendering. It can be either the Maya Render View or 3Delight Display.
The Image Viewer option specifies the location of the applications that will be launched to view images. The default application is 3Delight Display.