A lock for sliding closet doors?

We have large, mirrored closet doors in all of the bedrooms in our house. My DD is facinated with opening them and pulling things out of the closet. Does anyone know of a safety lock that will keep the doors closed?

It isn't a really good one, but I have seen one that sticks to the mirror. It is kind of shaped like skateboard - flat in the middle with two flexible tips, the tips prevent the doors from sliding, but you can press down on the tips so that they go flat and slide between the doors. That is rather complicated sounding for something that is rather basic...

Here is a link to the safety 1st version:
http://www.safety1st.com/product.asp?productID=600

Jen in Okinawa
Mom to a wonderful preschooler,
who is 3 1/2, Noelle!