PropertiesEditor tree issue

I'm seeing a weird thing happening with the tree view of the
PropertiesEditor plugin: when I comment out some properties
the root of the tree doesn't disappear.

i.e.:
Create a new properties file
type in two properties:
a.b.c=foo
a.b.d=foo

the tree shows
a
- b
- c
- d

Comment out a.b.c=foo with a '#'
Comment out a.b.d=foo with a '#'

Now the tree shows:
a

Uncomment and recomment just the second line, now
the tree shows:
a
a

The keep accumulating, too. Interesting :)

Vince.