Use the ExpandOnDblClick property to disable expanding or collapsing items when user dbl clicks an item. By default, the ExpandOnDblClick property is True. Use the ExpandOnKeys property to specify whether the control expands or collapses a node when user presses arrow keys. The ExpandOnSearch property specifies whether the control expands nodes when incremental searching is on ( AutoSearch property is different than 0 ) and user types characters when the control has the focus. The control fires the DblClick event when user double clicks the control. Use the ExpandItem property to programmatically expand or collapse an item.