This example demonstrates how to force a user to call Spell Checker before the changed content be submitted.

<obout:Editor runat="server" Id="editor" Width="100%">
    <EditPanel Height="360px" OnClientLoaded="editPanelLoaded" ImmediateValidation="false" />
    <BottomToolBar ShowHtmlTextButton="false" />
</obout:Editor>
<asp:CustomValidator id="CustomValidator1"
    ControlToValidate="editor" ClientValidationFunction="ClientValidate"
    Display="None" runat="server"/>

...
<script type="text/javascript">
  // on EditPanel loaded
  function editPanelLoaded(sender, args) {
       // by default the initial mode is 'Design'
       var designPanel = sender.get_activePanel();
       // get the 'Editor' component
       var editor = sender.get_owner();
       // get the top toolbar
       var topToolbar = editor.get_topToolbar();
       // get all buttons of the top toolbar
       var buttons = topToolbar.get_buttons();
       // try to find the 'SpellCheck' button
       for (var i = 0; i < buttons.length; i++) {
           var button = buttons[i];
           if (button.get_buttonName() == "SpellCheck") {
               // get the PopupHolder used for the spell checker popup
                var popupHolder = button.get_popupHolder();
               // add event handler to the PopupHolder component
               popupHolder.add_popupStateChanged(function (sender, args) {
                   // some popup closed
                    if (args.get_state() == Obout.Ajax.UI.HTMLEditor.PopupStateType.Close) {
                       // 'Spell checker' popup
                       if (args.get_name().split(",")[0] == "Obout.Ajax.UI.HTMLEditor.Popups.SpellCheckPopup") {
                           setTimeout(function () {
                               // set our 'Spell checked' indicator
                               designPanel.__contentChecked = true;
                           }, 100);
                       }
                   }
               });
               // set our 'Spell checked' indicator
               // we suppose that initial content is correct
               designPanel.__contentChecked = true;
               // intercept 'content changed' event
               designPanel.add_contentChanged(function (sender, args) {
                   // reset our 'Spell checked' indicator
                   sender.__contentChecked = false;
               });
               break;
           }
       }
  }
  // for custom validator
  function ClientValidate(source, arguments) {
       // get the Editor component
       var editor = $find("<%= editor.ClientID %>");
       var designMode = Obout.Ajax.UI.HTMLEditor.ActiveModeType.Design;
       // get the DesignPanel component
       var designPanel = editor.get_editPanel().get_modePanels()[designMode];
      
       // check our 'Spell checked' indicator
       if (designPanel.__contentChecked) {
           arguments.IsValid = true;
       } else {
           arguments.IsValid = false;
           setTimeout(function () {
               alert("Call 'Spell checker' before!");
           }, 0);
       }
  }

</script>