The 3Delight Preferences Dialog
These screenshots have to be taken again with less 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.) TW: 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 first section of this tab contains the Render View option preference is for selecting the window (and application) in which image layers will be layers are displayed on screen during rendering. See Image Layers (AOVs). 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 (a.k.a i-display).