Collapse and expand in GtkTreeView

[Christoph Schmeding <cschmeding altair com>]

Hello!

When I expand an item in a GtkTreeView that I just collapsed before, 
only the first child level of the expanded item is shown.

Example:
Before collapsing:
- Item 1
  - Item 11
     - Item 111
     - Item 112
  - Item 12

After collapsing Item 1 and re-expanding it:
- Item 1
  - Item 11
  - Item 12

Is there a possiblity (a property or whatever) to get the same state as 
before collapsing, or do I have to handle it myself?

Thanks,
Christoph