Using Namespaces and element visibility.

[ChrisBD]

I have been playing around with Namespaces and element visibility.
I was hoping to use them as a means of hiding package elements from use across packages.
Is this possible?
For example:
If I set Package1 and Package2 each to be namespace roots and each package contains Class1, Class2, Class3.
These can be referred to as Package1::Class1, Package1::Class2, Package1::Class3, Package2::Class1, Package2::Class and Package2::Class3.
I have tried changing the scope of these classes so that only Package1::Class1 and Package2::Class2 are public but when I try to "Insert Existing Element" on a diagram within Package2 and change the namespace filter to Package1 I am still able to added Package1::Class2 and Package1::Class3 even though they had private scope.

Am I missing something here?