Prerequisites Create a course with a page activity Have the TinyMCE as the prefered editor. Test instructions First part Edit the page activity, change to the source view in the Tiny and add the following text: <table> <tbody> <tr> <td class="styleid"> <button class="button" onclick="alert('horray')">click me</button></td> </tr> </tbody> </table> Hit the Save button to switch back to WYSIWYG mode. Go back to the source code button. Expected outcome: the onclick attribute vanished. Second part Change the settings, go to the Site administration -> Plugins -> Text editors -> TinyMCE editor -> General settings. Change the value of editor_tiny | extended_valid_elements to script [*] ,p [*] ,i [*] ,button [onclick] and click save. Go to the page activity, repeat the steps from above. Expected outcome: This time after switching back from the WYSIWYG mode again into the source code mode, the onclick attribute should be still inside the button element.