The GetLinksUseSmallImage method returns true or false depending on whether the group's links uses small or large images.
The "VSToolBoxView" view does not support large images. So if this view is applied, the GetLinksUseSmallImage method will always return true.
For other views, the size of the links' images is controlled by the GroupStyle property. The GetLinksUseSmallImage function will return true if this property is set to NavBarGroupStyle.SmallIconsList or NavBarGroupStyle.SmallIconsText.