When does manga become manga?

If a westerner draws, say, this:

http://farm2.static.flickr.com/1320/941340905_690207c8d4.jpg

It counts as a drawing done in a manga-style. Why not manga? When does it become manga? Is it only when a native Japanese artist draws it? If so, if a Japanese person drew a standard smiley face, does that count as manga?

We call the jap stuff manga because of the "style" its done in with layout. If a westerner draws something it = comics.