bloquear combobox

Private Sub cb_tareas_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles cb_tareas.MouseDown
        If e.Button = MouseButtons.Right Then
            cb_tareas.DroppedDown = True
        End If
    End Sub

    Private Sub cb_tareas_KeyDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles cb_tareas.KeyDown
        e.SuppressKeyPress = True
    End Sub

    Private Sub cb_tareas_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles cb_tareas.KeyPress
        e.Handled = True
    End Sub