I assume you are using WinForms.
If you work with one choice, it is quite simple: on the double-click handler (please check how to do this with Google or see later) check the property SelectedItem. A double-click item is also selected.
void OnMouseDoubleClick(object sender, MouseEventArgs e)
{
var list = (ListBox)sender;
object item = list.SelectedItem;
}
If you are working with multiple selections, you need to check more which item was clicked because it may be the last selection, you can use the method IndexFromPoint()as follows:
void OnMouseDoubleClick(object sender, MouseEventArgs e)
{
var list = (ListBox)sender;
int itemIndex = list.IndexFromPoint(e.Location);
if (itemIndex != -1)
{
object item = list.Items[itemIndex];
}
}
EDIT ? Google - , , , , MouseDoubleClick. , ...