Hi Adam

 

Have found a fudge that works, it may help you in debugging etc.

 

  var txtToInsert = 'This is the html and script etc to insert';

  var txt = document.getElementById('<%= editor1.ClientID %>');
 txt.SetActiveTab('code');
  txt.ExecCommand('SelectALL', false, 'SelectAll');
  txt.ExecCommand('pastetext', false, txtToInsert);
 txt.SetActiveTab('edit');