HAS-CHILDREN (numeric)

When set to a non-zero value, this special property indicates that the item identified by ITEM has child items even if there are no child items in the control. When set to zero (the default), an item has children only if they are physically present in the control. This property is useful when it is impractical to place all of a tree's items in the control all at once. In this approach, you don't place child items in the tree, but you mark which items have children via this property. Then, when the user expands a particular item, you have the program respond to the MSG-TV-EXPANDING event by adding the appropriate child items to the control. The HAS-CHILDREN property informs the control which items can be expanded.