Trouble with click -> drag and GTK_SELECTION_MULTIPLE

[Ken Siersma <siersmak ekkinc com>]

Another issue with my GtkTreeView that I can't figure out:

I want the user to be able to select multiple entries in my list by 
clicking on one entry and draggin the mouse down the list.  I have:

Wlist = gtk_tree_view_new();
sel = gtk_tree_view_get_selection(GTK_TREE_VIEW(Wlist));
gtk_tree_selection_set_mode(sel, GTK_SELECTION_MULTIPLE);

which, according to the API, should allow the behavior I'm looking for:

GTK_SELECTION_MULTIPLE Any number of elements may be selected. Clicks 
toggle the state of an item. Any number of elements may be selected. 
*Click-drag selects a range of elements*; the Ctrl key may be used to 
enlarge the selection, and Shift key to select between the focus and the 
child pointed to.

But it doesn't seem to work.

Anyone else seen this?
Ken