property Editor.ExpandItem(Value as Variant) as Boolean
Expandes or collapses an item in the editor's list.

TypeDescription
Value as Variant A long expression that indicates the value of the item being expanded, a string expression that indicates the caption of the item being expanded.
Boolean A boolean expression that indicates whether the item is expanded or collapsed.
[not supported yet] By default, the items are collapsed. Use the ExpandItem to expand a specified item. Use the ExpandAll method to expand all items in the editor. Use the InsertItem method to insert a child item to your built-in editor