If you guys visit Yahoo Photos, there is a link to edit image.
Something like http://up.photos.yahoo.com/ed/YourYahooUserName/edp. On
that page, there is a "red eye" option. You can move your mouse over a
static image and draw a rectangular region interactively. Once you
release your mouse left button, a small image correspondent to the
region was pop up. I was surprised because html are not able to handle
interactive user action. Does anyone know how this function is
implemented?

Thanks,

Autogoor