DesktopListBox.AddExpandableRowAt
From Xojo Documentation
Method
DesktopListBox.AddExpandableRowAt(rowNumber as Integer, Item as String, [Indent as Integer])
New in 2021r3
Supported for all project types and targets.
New in 2021r3
Supported for all project types and targets.
Creates a new expandable row at row, moving the existing rows down. The text is always assigned to column zero. The optional parameter indent specifies the amount of indentation of the row in a ListBox where AllowExpandableRows (sometimes called a hierarchical ListBox) is True. The default is zero. It has no effect on a ListBoxe where AllowExpandableRows is False.
Example
The following example in a DesktopButton adds a row to the ListBox with expandable rows that is used for the example in AddExpandableRow. It simply adds a new state to the list of cities and states.
Listbox1.AddExpandableRowAt(1, "New Hampshire")