This property returns and sets a value that specifies which item in a ComboBox or ListBox control is displayed in the uppermost position.
object.TopIndex [= value]
The TopIndex property is unavailable at design time.
Use this property to scroll through a control without selecting an item.
If the Columns property is set to 0 for the ListBox control, the item is displayed at the uppermost position if there are enough items below it to fill the visible portion of the list.
If the Columns property setting is greater than 0 for the ListBox control, the item's column moves to the leftmost position without changing its position within the column.