I created a style enabling spell-checking for all TextBoxes within the scope of my grid and got spell checking to work in the text editors.

<Style TargetType="{x:Type TextBox}">
    <Setter Property="SpellCheck.IsEnabled" Value="True"/>
</Style>

Also, John, if you are using XAML anywhere near the scope of your grid, you can define your styles there (perhaps in the container for the grid).

I've also tried styling the TextBox (instead of the XamTextEditor) as shown below. But this still word-breaks strangely! Attached in a screenshot, notice that 'wor' of the word 'work' is shown as a spelling error!

Any ideas?

BTW I'm having to construct my styles in code rather than XAML because I'm dynamically building all this from db tables.

textboxstyle.Setters.Add(new EventSetter(TextBox.LoadedEvent, new RoutedEventHandler(SpellCheckLoaded)));

editorstyle.Resources.Add(typeof(TextBox), textboxstyle);

...

 private static void SpellCheckLoaded(object sender, RoutedEventArgs e)
  {
   ((TextBox)sender).SpellCheck.IsEnabled = true;
  }

A MaskEditor will spell check by default? I don't see any options in your code to turn spell checking on..

Try this:

Create a cutom Field which his editor is XamMasketTexbox. 

then assume that f is an object of typeField and configure it:

                    f.DataType = typeof(string);
                    f.Settings.EditAsType = typeof(string);
                    f.Settings.EditorType = typeof(XamMaskedEditor);

                    Style s = new Style(typeof(XamMaskedEditor));
                    //Setter setterMask = new Setter(XamMaskedEditor.MaskProperty, mask);
                    Setter setterMask = new Setter(XamMaskedEditor.MaskProperty, "{char:10:0-9a-zA-Z)");
                    s.Setters.Add(setterMask);
                    f.Settings.EditorStyle = s;
 

 If you need a list of rules to generarte masks follow this link:

http://help.infragistics.com/Help/NetAdvantage/WPF/2007.2/CLR3.X/HTML/xamEditors_Masks.html

Andrea