Web Publishing Wizard

Hello all,

I have a small question. I m trying to create a web publishing wizard for xp
(and it works) but i would like to restrict the file format. So i've read the
msdn and add a

window.external.Property("UniqueExtensionN")=array(".jpg",".jpeg");

to my php script witch generate the wizard interface. And i add a
"supportedtypes" = "*.jpg;*.jpeg"

to my registry key but it doesn't work the wizard send any type of document
to my server.

How can i do ? i don't want to filter it on my server but on client-side.

Thx by advance for your answers