Well, in the specific case of the query.edit page, the consequence was
that all queries were shown as 'private', whether they were or not, and
then when the form was submitted for any reason, all queries were set to
private, whether they were before or not, unless you had changed them
back before submitting.

In general the problem is that if a LinkHTMLProperty is None, and you
try to *test* that it is None using == (you can't use 'is', obviously,
which is a different but unavoidable problem), things don't work as you
expect, and (the big problem) the failure is silent.

I will try the test suite when I have time (later today, with any luck).