Gtk2::TreeView and friends: set_selectable()?

[Martin Junius <mj+gnome ml m-j-s net>]

Hi all!

In the progress of converting a CTree application to TreeView/TreeStore 
I came across the following, where I haven't found an answer to yet:

How do I make specific rows un-selectable? With CTree I'd be using 
something like
    $tree->node_set_selectable($node, 0);
Any ideas or hints?

Martin