[Vala] Gtk.TreeView: void* in vapi

[JM <interflug1 gmx net>]

Hello

I need some help with the binding for TreeViewRowSeparatorFunc.
Something is wrong here.
If I use

  this.set_row_separator_func(separator_func, null, destrnot);

in my TreeView widget together with
        
  public static void destrnot() {
    return; //just for testing
  }
        
  private bool separator_func(Gtk.TreeModel model, Gtk.TreeIter iter) {
   print("in TreeViewRowSeparatorFunc\n");
   return false; //just for testing
 }

I get the following ccode:

  gtk_tree_view_set_row_separator_func (
     (GtkTreeView*) self,
_xnoise_media_browser_separator_func_gtk_tree_view_row_separator_func,
self, 
NULL, 
_xnoise_media_browser_destrnot_gdestroy_notify);

The vapi file says:

  public void set_search_position_func (Gtk.TreeViewSearchPositionFunc
func, 
void* data, 
GLib.DestroyNotify destroy);

I'm not sure how vala handles void* but obviously in the ccode there is
one too many 'self'. 

Can anybody give me a hint how to correct the vapi? 

Regards
Jörn