Gtk2::CellRendererText font issue

[Chas Owens <alas wilma widomaker com>]

I have set the font for a Gtk2::TreeView by saying

my $list     = Gtk2::TreeView->new($store);
my $renderer = Gtk2::CellRendererText->new;
$renderer->set("editable", 1);
$renderer->set("font", "Monospace 20");

my $i;
for my $col (@cols) {
        $list->append_column(
                Gtk2::TreeViewColumn->new_with_attributes(
                        $col,
                        $renderer,
                        text => $i++
                )
        );
}

and it works.  Or at least it works until I go to edit a cell.  Then the font drops back to original size.  
When I am finished editing it jumps back.   Is there some way to set the font size for editing?