This document covers the following topics:
If not suppressed, this event is received by a tree view control when the user attempts to expand a tree view item to show its child items (if any).
The program can query the control's ITEM attribute to determine which tree view item is being expanded. Before this event is raised, this item's EXPANDED attribute will have already been set to TRUE. However, if the program resets this attribute to FALSE within this event, the expansion does not occur.
At the time this event is raised, the child items have not yet been shown, allowing the child items to be created or destroyed dynamically without any transition effects being visible to the user.
For more information, please refer to the article Working with Tree View Controls.