MSG-TV-DBLCLICK
This event is fired when the user double-clicks a tree-view item without children. If the
Has-Children property of the item is set to 1, then the
MSG-TV-EXPANDING event is fired instead.
EVENT-DATA-2 contains the ID of the selected item.
If the Tree-View has the
Table-View style, the EVENT-DATA-1 data item contains the column index.