Ctrl + K still works when IsReadOnly=True

[Bruce]

this.radRichTextEditor.IsReadOnly = true;

still allow you to add hyperlink the document body.

[Hristo]

Hi Bruce,

Thank you for writing.

Indeed the observed behavior is an issue and I have logged it in our feedback portal, here: FIX. RadRichTextEditor - the InsertHyperlinkDialog can still be opened using the Ctrl + K key shortcut even when the control has its IsReadOnly property set to true. I have also updated your Telerik points. 
The item is already in development and a fix will be made available with our  R3 release scheduled for mid-September.

Until the release please handle the CommandExecuting event and cancel it if the control is read-only and the command is ShowInsertHyperlinkDialogCommand: 

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        this.radRichTextEditor1.IsReadOnly = true;
        this.radRichTextEditor1.CommandExecuting += RadRichTextEditor1_CommandExecuting;
    }

    private void RadRichTextEditor1_CommandExecuting(object sender, Telerik.WinForms.Documents.RichTextBoxCommands.CommandExecutingEventArgs e)
    {
        if (this.radRichTextEditor1.IsReadOnly && e.Command is ShowInsertHyperlinkDialogCommand)
        {
            e.Cancel = true;
        }
    }
}

I hope this helps. Should you have further questions please do not hesitate to write back.

Regards,
Hristo
Progress Telerik