Set this attribute to the desired sort mode. When you are using Listtree.Insert
with Sorted or dropping an entry on a closed node, this sort hook is used.
The following values are possible here:
Head-
Any entry is inserted at head of the list.
Tail-
Any entry is inserted at tail of the list.
LeavesTop-
Leaves are inserted at top of the list, nodes at bottom. They are
alphabetically sorted.
LeavesMixed-
The entries are only alphabetically sorted.
LeavesBottom-
Leaves are inserted at bottom of the list, nodes at top. They are
alphabetically sorted. This is the default.