Drop the tree model before updating transaction association tree view

To avoid delays with large transaction associations trees, drop the
model from the transaction association tree view while it is being
updated and then reconnect it after the model has been updated.

gnucash/gnome/dialog-trans-assoc.c

@@ -165,7 +165,10 @@ assoc_dialog_update (AssocDialog *assoc_dialog)
     GtkTreeIter       iter;
     gboolean          valid;
 
+    /* disconnect the model from the treeview */
     model = gtk_tree_view_get_model (GTK_TREE_VIEW(assoc_dialog->view));
+    g_object_ref (G_OBJECT(model));
+    gtk_tree_view_set_model (GTK_TREE_VIEW(assoc_dialog->view), NULL);
 
     /* Get first row in list store */
     valid = gtk_tree_model_get_iter_first (model, &iter);
@@ -205,6 +208,9 @@ assoc_dialog_update (AssocDialog *assoc_dialog)
         g_free (filename);
         valid = gtk_tree_model_iter_next (model, &iter);
     }
+    /* reconnect the model to the treeview */
+    gtk_tree_view_set_model (GTK_TREE_VIEW(assoc_dialog->view), model);
+    g_object_unref(G_OBJECT(model));
 }
 
 static void
@@ -299,7 +305,10 @@ get_trans_info (AssocDialog *assoc_dialog)
     /* Get list of Accounts */
     accts = gnc_account_get_descendants_sorted (root);
 
+    /* disconnect the model from the treeview */
     model = gtk_tree_view_get_model (GTK_TREE_VIEW(assoc_dialog->view));
+    g_object_ref (G_OBJECT(model));
+    gtk_tree_view_set_model (GTK_TREE_VIEW(assoc_dialog->view), NULL);
 
     /* Go through list of accounts */
     for (ptr = accts; ptr; ptr = g_list_next (ptr))
@@ -352,6 +361,11 @@ get_trans_info (AssocDialog *assoc_dialog)
         qof_query_destroy (query);
         g_list_free (splits);
     }
+
+    /* reconnect the model to the treeview */
+    gtk_tree_view_set_model (GTK_TREE_VIEW(assoc_dialog->view), model);
+    g_object_unref(G_OBJECT(model));
+
     g_list_free (accts);
     g_list_free (trans_list);
 }