.NET (Core and Framework)

Private Sub ListBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles ListBox1.MouseDown<br />
    Dim item As Integer<br />
    For j As Integer = 1 To ListBox1.Items.Count<br />
        Dim rect As System.Drawing.Rectangle = ListBox1.GetItemRectangle(j - 1)<br />
        If rect.Contains(e.X, e.Y) Then<br />
            item = j - 1<br />
            Exit For<br />
        End If<br />
    Next<br />
    ListBox1.SelectedIndex = item<br />
End Sub