It *is* possible to prevent image stealing by
disabling sellecting the image, whether you are on
a mac or not.  And it *is* possible to write the
code so the source is hidden in another file that
cannot be viewed...hence there is no way to simply
find the URL of the image and view the image
directly from the URL.  BUT, you are correct in
the sense that if someone is an expert
hacker...they could probably hack into your system
(..the system your keep your webpage on) and
directly copy the image.

  Whether you want to watermark or simply disable
someone from ever downloading or linking to the
image is up to you.  It's all a matter of
preference.

  
joyka