This event occurs when the selection has changed in a Tree View control. The ID of the new item is contained in EVENT-DATA-2. EVENT-DATA-1 contains the cause of the change. It is one of the following values (found in acugui.def):
| TVFLAG MOUSE | New item selected with mouse |
| TVFLAG KEYBOARD | New item selected with keyboard |
| TVFLAG PROGRAM | Program changed selected item |