A tree view control notifies the parent window when the selection changes from one item to another by sending the TVN_SELCHANGING and TVN_SELCHANGED notification messages. The notifications also include data about the item that gains the selection and the item that loses the selection. You can use this data to set item attributes that depend on the selection state of the item. Returning TRUE in response to TVN_SELCHANGING rejects the selection change and returning FALSE accepts the selection change. Change the selection by sending the TVM_SELECTITEM message.
Tree view controls support a number of messages that retrieve data about items in the control.
The TVM_GETITEM message can retrieve an item's handle and attributes. An item's attributes include its current state, the indexes in the control's image list of the item's selected and unselected bit images, a flag that indicates whether the item has child items, the address of the item's label string, and the item's application-defined 32-bit value.
The TVM_GETNEXTITEM message retrieves the tree view item that bears the specified relationship to the current item. The message can retrieve an item's parent, the next or previous visible item, the first child item, and so on.
The TVM_GETITEMRECT message retrieves the bounding rectangle for a tree view item. The TVM_GETCOUNT and TVM_GETVISIBLECOUNT messages retrieve a count of the items in a tree view control and a count of the items that can be fully visible in the tree view control's window, respectively. You can ensure that a particular item is visible by using the TVM_ENSUREVISIBLE message.