richTextBox 颜色控制

    Private Sub output(ByVal str As String, ByVal color As Color)
        '默认色 SystemColors.WindowText，灰色 Color.Gray，红色 Color.Red，绿色 Color.Green，橘红 Color.OrangeRed
        richTextBox.SelectionColor = color
        richTextBox.AppendText(str & vbCrLf)
        richTextBox.ScrollToCaret()
    End Sub