Assistants, even incorporating "tricks" and sound effects. If the user wishes, they can also turn off the animated character entirely. The search capability itself is fairly similar to Windows Me and Windows 2000, with some important additions. The Indexing Service can extract Exif properties, as well as some metadata for ASF, WMV and MP3 files under Windows XP via the IPropertyStorage interface using built-in Null Filter. Search can also be instructed to search only files that are categorically "Documents" or "Pictures, music and video" (searching by perceived type); this feature is noteworthy largely because of how Windows determines what types of files can be classified under these categories. Another important addition is that the "Look in" field accepts and expands environment variables for abbreviated entry of long paths. Also, users can configure whether or not Windows XP searches for system and/or hidden files and folders. Using Tweak UI, the search user interface can be restored to the one used by Windows 2000. Image handling in Explorer Windows XP improves image preview by offering a Filmstrip view which shows images in a single horizontal row and a large preview of the currently selected image above it. "Back" and "Previous" buttons facilitate navigation through the pictures, and a pair of "Rotate" buttons offer 90-degree clockwise and counter-clockwise rotation of images. Filmstrip view like any other view can be turned on per folder. This view will be available if the new "Common Tasks" folder view is selected, not with "Windows Classic" folder view. Aside from the Filmstrip view mode, there is a 'Thumbnails' view, which displays thumbnail-sized images in the folder and also displays images a subfolder may be containing (4 by default) overlaid on a large folder icon. A folder's thumbnail view can be customized from the Customize tab accessible from its Properties, where users can also change the folder's icon and specify a template type (pictures, music, videos, documents) for that folder and optionally all its subfolders. The size and quality of thumbnails in "Thumbnails" view can be adjusted using Tweak UI or the registry. Exif metadata stored in the image is also shown in the file's Properties -> Summary tab, in "Details" view and in any view on the status bar. Windows XP optionally caches the thumbnails in a "Thumbs.db" file in the same folder as the pictures so that thumbnails are generated faster the next time. Thumbnails can be