NB: More recent documentation for Dyalog APL is available at https://docs.dyalog.com/20.0/.

HeaderImageIndex Property
Applies To: ListView

Description

The HeaderImageIndex property is an integer vector that specifies the images to be displayed alongside each column heading in a ListView object in Report View. Each positive element of HeaderImageIndex specifies an index into the ImageList object specified by the HeaderImageList property. The special values ¯1 and ¯2 specify the standard Sort Up and Sort Down images respectively.