Complete the following steps to set the type of symbol to display next to each item that has other items indented under it. You can use the expand/contract symbols to open and close parent items in the tree.
You also can use the Expand/Contract Symbol:Symbol Type property to set programmatically the type of symbol to display next to each parent item.
Right-click a tree control and select Expand/Contract Symbol Type»Show at Indent Level 0 from the shortcut menu to show or hide the expand/contract symbols for items at the highest level of the hierarchy. If you remove the checkmark next to this option, you can still expand or collapse an item at indent level 0 by double-clicking the item. To disable the double-clicking functionality, wire a True constant to the Discard? parameter of the Item Close? event.
You also can use the Expand/Contract Symbol:Show Symbol at Root property to show or hide the symbols programmatically.