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ListBox.TopIndex Property

Gets or sets the index of the first visible item in the ListBox.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)
[BrowsableAttribute(false)]
public int TopIndex { get; set; }

Property Value

Type: System.Int32
The zero-based index of the first visible item in the control.

Initially, the item with the index position zero (0) is at the top of the visible region of the ListBox. If the contents of the ListBox have been scrolled, another item might be at the top of the control's display area. You can use this property to obtain the index within the ListBox.ObjectCollection for the ListBox of the item that is currently positioned at the top of the visible region of the control. You can also use this property to position an item in the list at the top of the visible region of the control.

The following code example demonstrates how to use the SelectedIndex property with the TopIndex property to move the currently selected item to the top of the list of items in the display area of the ListBox. The example further demonstrates how to remove items using the RemoveAt method of the System.Windows.Forms.ListBox.ObjectCollection class, and how to clear all item selection using the ClearSelected method. The code first moves the currently selected item in the ListBox to the top of the list. The code then removes all items before the currently selected item and clears all selections in the ListBox. This example requires that a ListBox containing items is added to a form and that an item is currently selected in the ListBox.


private void RemoveTopItems()
{
   // Determine if the currently selected item in the ListBox 
   // is the item displayed at the top in the ListBox.
   if (listBox1.TopIndex != listBox1.SelectedIndex)
      // Make the currently selected item the top item in the ListBox.
      listBox1.TopIndex = listBox1.SelectedIndex;

   // Remove all items before the top item in the ListBox.
   for (int x = (listBox1.SelectedIndex -1); x >= 0; x--)
   {
      listBox1.Items.RemoveAt(x);
   }

   // Clear all selections in the ListBox.
   listBox1.ClearSelected();
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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