MSG-TV-SELCHANGE
This event is fired when the user changes the selected item in a Tree-View control. The EVENT-DATA-2 data item contains the newly selected item. EVENT-DATA-1 contains one of the following symbolic values, defined in 
isgui.def, depending on the reason of the change.
TVFLAG-MOUSE  | The new item has been selected with the mouse.  | 
TVFLAG-KEYBOARD  | The new item has been selected with the keyboard.  | 
TVFLAG-PROGRAM  | The new item has been programmatically selected by setting the  Value property.  |