This just started happening to me in 5.1.1716.7. I was typing this:
Yet when I hit "." I get this expanded out:
My file has a using System.Windows at the top of it.
Note that this is inside of a ListBox-derived class. I'm guessing the fact that it has a property named "Visibility" is confusing it. Also, if I undo the above change and type "." again I get a different version that is the members of the local Visibility property, which is also something I don't want.
The Intellisense behavior built into VS2010 has the best behavior. It (a) does not ever expand out to System.Windows.Visibility and (b) handles the ambiguity by combining both the local enum property and the global type into a single listbox.