I just created a razor macro with the following code:
I created a macro from that and added a parameter named hString. I also ticked the Use in editor checkbox.
Now when I go to tinyMCE and insert the macro I get a text box. In it I put: <a href="bla.html">Bla</a>. When I click save I get:
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.ArgumentOutOfRangeException: Length cannot be less than zero.Parameter name: length