By default, the OverlayIcons property is True, which indicates that the control displays the overlay icons. Windows uses Overlay-ed icons to notify the user that some item has special function or attribute. For example, shortcut icons have a small arrow in lower-left corner, shared folders have a hand that shows that folder is shared, etc. The ViewMode property indicates the way the shell displays the files/folders inside.

The following screen shot shows the shell view with overlay icons:

while the next screen shot shows the shell view with no overlay icons: