Proper Handling of GtkTreeModelFilters

["Matthew Yaconis" <myaconis nycap rr com>]

I have an underlying model for a TreeView in my application that I am 
filtering based on certain user selections.  I maintain a global reference 
to the "base" TreeModel (which is sometimes attached to the TreeView used to 
display the information.)  The mechanism I am using goes something like 
this:

1.  User selects a new filter criteria
2.  (Depending on the selection) Either a) gtk_tree_model_filter_new to 
create a new filter based on the user's criteria from the global "base" 
model or b) use the base model.
3.  gtk_tree_view_set_model( [selected model])

I was thinking this is probably leaving a bunch of filtered tree models 
around that aren't doing anything but taking up space...do I need to be 
g_object_unref'ing the old filter models?  I attempted a "replace" function 
that looks something like:

void replaceTreeModel(GtkTreeModel *model)
{
   GtkTreeView *treeview = [get the widget];
    GtkTreeModel *currentModel = gtk_tree_view_get_model(treeview);

   gtk_tree_view_set_model( treeview, model );

   // The following makes the application unstable and crash in the filter 
function so I've commented it out for now
   //if (GTK_IS_TREE_MODEL_FILTER( currentModel))
   //{
   //   g_object_unref( G_OBJECT(currentModel));
   //}
}

What is the best/proven way of doing something like this?

Thanks,

Matt