[Kde-kiosk] Preventing directory browsing

[Prash]

Hi guys,

I've been working on locking down my desktop in a reproducible way. So
I changed permissions on .desktop and .directory files to 640 i.e non
root users will not be able to launch it. I added lots of restrictions
in /usr/share/config/kdeglobals file as mentioned in readme file. I
also removed files from the $HOME/desktop folder and made it owned by
root.
Everything works fine and I have my menu exactly as I want i.e games,
browser, xine and cd player. The only problem is preventing users from
browsing directories - I want to restrict browsing only one directory
- say the 'downloads' directory. They haven't got access to any shell
or anything - all they have is KDE.  They can browse directories using
file->open , file-> save etc.
How can I restrict them to just one directory? This becomes important
as I don't want them to browse $HOME/.kde folder and change the files.
(They cannot see hidden files)

TIA