public IntPtr GetHBitmap(int iconSize, bool isThumbnail, bool isForce = false) {
ThumbnailOptions options = ThumbnailOptions.None;
if (isThumbnail) {
options = ThumbnailOptions.ThumbnailOnly;
if (!isForce)
options |= ThumbnailOptions.InCacheOnly;
} else {
options |= ThumbnailOptions.IconOnly;
}
return WindowsThumbnailProvider.GetThumbnail(this.PIDL, iconSize, iconSize, options);
}