Hello James.Jeon,

You can handle MouseLeftButtonUp event and get which link is clicked, and then write your business logic based on the clicked link.

private void xamRichTextEditor1_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    var editor = sender as XamRichTextEditor;

    if (editor == null)
    {
        return;
    }

    var docSpan = editor.Selection.DocumentSpan;
    var paragraphs = editor.Document.GetParagraphs(docSpan);

    if (paragraphs.First().ChildNodes == null)
    {
        return;
    }

    var hyperlink = paragraphs.First().ChildNodes.First() as HyperlinkNode;
    if (hyperlink != null)
    {
        if (hyperlink.Uri.Contains("forums"))
        {
            //DoSomeAction();
            Process.Start(hyperlink.Uri);
        }
        else
        {
            //DoAnotherAction();
            Process.Start(hyperlink.Uri);
        }
    }
}

If you have any question with this, please let me know.

Best regards,
Yuki Mita
Developer Support Engineer
Infragistics Inc.
www.infragistics.com/support

Thank you so much about your guide.

May I ask one more thing?

In my program, I subscribe  XamRichTextEditor.HyperlinkExecuting event  to use  Uri property of HyperlinkExecutingEventArgs because I want different actions when user click the hyperlink.

I don't know How can I pass the Uri String into text_PreviewMouseDown() cause it argument is not HyperlinkExecutingEventArgs but MouseButtonEventArgs.

Please let me know how I can do this. 

Below are snippet what I want to do.

// MainWindow Code-Behind

public MainWindow()

{

     InitializeComponent();

     richText.HyperlinkExecuting += richText_HyperlinkExecuting;     

}

private void richText_HyperlinkExecuting(object sender, HyperlinkExecutingEventArgs s)

{

    if (e.Uri.StartsWith("AAA")

       DoSomeAction();

    if (e.Uri.StartsWith("BBB")

       DoAnotherAction();

    e.Cancel = true;

}

To Sum it up, I like to call hyperlinkExecuting Event with direct click (not ctrl + click) with Cursors.Hand.

Thank you so much.