PanedBox Bug?

[David Robin <david robin st com>]

I Created a H-Paned Box with a notebook in each of the panels with gtk_panel_add.
When I hide the left notebook, the left panel goes hidden. But the right notebook doesnot takes  the empty space, and the gutter stays visible. Is it the expected
behaviour?
The behaviour I expected was : when I 'kind of' close one of the panel, the other one fills all the space, and the gutter desappears because it is no more useful.
Then, If I show both notebooks again, the gutter reappears, at the same position it used to be.

Is this a bug, or do I need to add some code in my app and make it by myself?

Thanks,
                                          David.