Manually focusing a ctree node?

[Richard Harvey Chapman <hchapman 3gfp com>]

Summary: How can I set which node has the focus?

Under the extended selection mode for a ctree:

Select 2 or more nodes.
Hold down Ctrl and deselect one item. 
The item is deselected but holds the focus. 

I think this may be confusing for my users since I immediately update the
configuration page (that goes with the ctree) to reference the next
selected item in the selection list. Of course, the change only occurs if
the item deselected was the first item in the selection list.

How can I set which node has the focus?

BTW I think there's a bug in tree_select_row when using the extended
selection mode. The column number is sometimes unpredictable.

Thanks,

R.