The 3Delight Preferences Dialog
tab of the 3Delight Preferences.
Viewing Apps tab of the 3Delight Preferences.
The Viewing Apps Tab
The first section of this tab contains the Render View option for selecting the window (and application) in which image layers will be 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).