>>Before opening the form, perform SET DEFAULT TO to the directory containing the class. Seems that VFP has trouble finding the class if not in the path.
>
>It was in the path.
>
>Somehow this problem got finally resolved by itself. But sure took me several hours. The funny thing that at the end it was all in vain anyway - the nodefault in Page.Deactivate didn't work.
>
>Right now I'm trying to work it out from the other angle with the same unfortunate result so far.

Set procedure to, or set classlibrary to wherever the page is defined, then try to edit.