procedure TfrmDirectoryBrowser.FormCreate(Sender: TObject);
var
 SysIL: HIMAGELIST;
 Info: TSHFileInfo;
 SmallImages: TImageList;
begin
 SmallImages := TImageList.Create(Self);
 SysIL := SHGetFileInfo('', 0, Info, SizeOf(TSHFileInfo), SHGFI_SYSICONINDEX or SHGFI_SMALLICON);

 if SysIL <> 0 then
  begin
   SmallImages.Handle := SysIL;
   SmallImages.ShareImages := True;
   vstDirectoryBrowser.Images := SmallImages;
  end;
.....
end;

procedure TfrmDirectoryBrowser.vstDirectoryBrowserGetImageIndex(Sender: TBaseVirtualTree; Node: PVirtualNode; Kind: TVTImageKind; Column: TColumnIndex; var Ghosted: Boolean; var ImageIndex: Integer);
var
 NodeData: PDirectory;
 Info: TSHFileInfo;
begin
 NodeData := Sender.GetNodeData(Node);

 if NodeData^.iIconIndex = -1 then
  begin
   SHGetFileInfo(PChar(NodeData^.FullPath), FILE_ATTRIBUTE_NORMAL, Info, SizeOf(TSHFileInfo), SHGFI_SYSICONINDEX or SHGFI_SMALLICON);
   NodeData^.iIconIndex := Info.iIcon;
  end;

 ImageIndex := NodeData^.iIconIndex;
end;