TreeView notifications fix (take 2)

[Mike Hearn]

> Excellent! Now, in the light of this new finding, we have to reasses
> the listview situation. Did you get a chance to rerun Drew's tests
> for the listview?

No, not yet. I'm not convinced they are the same bug, Drews test cases
indicated the documented behaviour on Windows, whereas Mikes test case
showed incorrect behaviour for the listview on Windows.

On the other hand, you were right last time, so when I get some more
spare time I'll install mingw on my terminal server account and modify
the test case to use a listview instead and see what happens.