void _modest_header_view_size_cell_data (GtkTreeViewColumn *column, GtkCellRenderer *renderer,
GtkTreeModel *tree_model, GtkTreeIter *iter, gpointer user_data);
void _modest_header_view_status_cell_data (GtkTreeViewColumn *column, GtkCellRenderer *renderer,
void _modest_header_view_size_cell_data (GtkTreeViewColumn *column, GtkCellRenderer *renderer,
GtkTreeModel *tree_model, GtkTreeIter *iter, gpointer user_data);
void _modest_header_view_status_cell_data (GtkTreeViewColumn *column, GtkCellRenderer *renderer,