When non-nil, the value is a color spec or color alias determining the background color of the editor-pane cursor. See The Color System for information about color specs and aliases.
The value nil
means that the cursor background color is the same as the
foreground
color of the editor pane.
foreground
is a slot inherited from simple-pane.
CAPI User Guide and Reference Manual (Unix version) - 3 Aug 2017