kQLThumbnailOptionIconModeKey
The Quick Look generator produces the thumbnail as an icon with decor.
Declaration
let kQLThumbnailOptionIconModeKey: CFString!Discussion
The default value is kCFBooleanFalse. If you use the default, the Quick Look feature creates a thumbnail image with no icon decor. To create the thumbnail as an icon, set the value to kCFBooleanTrue. The icon’s image includes all the typical icon decor, such as shadows and a curled corner.