Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
        ' Determine the CheckState of the check box.
        If CheckBox1.CheckState = CheckState.Checked Then
            ' If checked, do not allow items to be dragged onto the form.
            Me.AllowDrop = False
        End If
End Sub