Disable DDE in file associations?

In NT-Explorer, when I try to edit an action associated
with a file type, if there's DDE enabled for that action,
I cannot remove it.

For example, I'm trying to edit the "Open" action for the
file type "GIF".

    From Explorer, View->Options
    Select the "File Types" tab
    Scroll down to "GIF Image", and select it
    Click Edit
    Select "Open" in the Actions list, and click Edit
    Uncheck the "Use DDE" box.
    Click OK

But ... it hasn't removed DDE!  Select "Open" again, and
click Edit, and you'll see that DDE is still there.