Colorize RichText log box

[Jeffrey Scott Humphreys]

I think things running, line could be italics, when done, go back to normal, and new line is bold saying complete.
Show time on right in green while running. gray when done.

var box = new RichTextBox
{
Dock = DockStyle.Fill,
Font = new Font("Courier New", 10)
};

box.AppendText("[" + DateTime.Now.ToShortTimeString() + "]", Color.Red);
box.AppendText(" ");
box.AppendText(userid, Color.Green);
box.AppendText(": ");
box.AppendText(message, Color.Blue);
box.AppendText(Environment.NewLine);

    box.SelectionStart = box.TextLength;
    box.SelectionLength = 0;

    box.SelectionColor = color;
    box.AppendText(text);
    box.SelectionColor = box.ForeColor;

Oops. above doesn't convert directly to Powershell

    $RunningActivityLog.SelectionStart = $RunningActivityLog.TextLength
    $RunningActivityLog.SelectionLength = 0
    $RunningActivityLog.SelectionColor = $textColor
    $RunningActivityLog.AppendText("$logtimestr`:$msg$([System.Environment]::NewLine)")
    $RunningActivityLog.ScrollToCaret()
    $RunningActivityLog.Refresh()