Confluence will index as text any file which has a mime type which isn't clearly non-text, so Wink files, which have a mime type of 'Wink Document' get indexed as text.

Files created with Wink give weird formated search results and much more irritating, the files let the search time increase several seconds per file.

How to verify?
1. upload confluence_test.wnk
2. wait for indexing
3. search for "teeest" (this word appears in confluence_test.wnk)