GtkTreeView and fixed_height mode

[Emmanuel Briot <briot adacore com>]

A customer of ours has recently moved from gtk+ 2.4 to gtk+2.8.
He was using the fixed_height mode to speed the rendering (time goes down from 
4 minutes down to 30s when it is activated, and that is still the case with 
gtk+ 2.8, so they of course want to preserve this setup).

However, there was one change in gtktreeview.c (which still exists in 
gtk+2.10): 


void
gtk_tree_view_set_fixed_height_mode (GtkTreeView *tree_view,
                                     gboolean     enable)
{
    [...]
      /* make sure all columns are of type FIXED */
      for (l = tree_view->priv->columns; l; l = l->next)
        {
          GtkTreeViewColumn *c = l->data;
          g_return_if_fail (gtk_tree_view_column_get_sizing (c) == 
GTK_TREE_VIEW_COLUMN_FIXED);

The assertion above checks that all columns are also using a fixed sizing. The 
comment doesn't really indicate *why* this was necessary though, and that is 
change compared to older versions of gtk+ 2.4.
I suppose changing their code to using fixed sizing for columns is doable, but 
what would they lose by doing that (is manual resizing an orthogonal issue 
for instance ?)

Thanks in advance for your comments
Emmanuel