TVirtualDrawTree.OnInitChildren Event

Node management event.

property OnInitChildren: TVTInitChildrenEvent;

In order to allow the tree only to fill content where needed it is possible to set the vsHasChildren style in a node's initializaton whithout really adding any child nodes. These child nodes must be initialized first when they are about to be displayed or another access (like search, iteration etc.) occurs. 

The application usually prepares data needed to fill child nodes when they are initialized and retrieves the actual number. Set ChildCount to the number of children you want.

The virtual paradigm

TVirtualDrawTree Class