property Thumbnail.ExtractMethod as String
Specifies the order and the methods the control uses to extract the thumbnails.

TypeDescription
String A String expression that specifies the list of methods the control uses to extract the thumbnails, separated by comma. If a method fails, the next one is trying to generate the thumbnail. The first one that succeeds the one is displayed.
By default, the ExtractMethod property is "ThumbnailCache,ThumbnailProvider,ExtractImage". The ExtractMedthod specifies the order and the methods the control uses to extract the thumbnails. 

The control is able to extract the thumbnail views using the following system interfaces: