In Windows/Qt, FileEditor selecting Desktop inserts extra user name

```
from os.path import expanduser
from traits.api import HasTraits, File, Unicode
from traitsui.api import FileEditor, Item, View

class Foo(HasTraits):
f = Unicode()
def _f_default(self):
return expanduser("~")

view = View(Item('f', editor=FileEditor(), show_label=False),resizable=True)
foo = Foo()
foo.edit_traits(view=view)
```
Note the default `style`.
Use the folder icon to open the native directory browser.
Navigate to the Desktop and choose "Open".
The resulting path has an extra `` appended after `Desktop`.

```
In [11]: traitsui.__version__
Out[11]: '6.0.0'
In [13]: pyface.__version__
Out[13]: '6.0.0'
```
PyQt version 4.12-1