When using CustomDictionary:

DocumentSpellChecker checker = this.radRichTextBoxResponses.SpellChecker as DocumentSpellChecker;
RadIsolatedStorageCustomDictionary dict = checker.GetCustomDictionary(new CultureInfo("en-US")) as RadIsolatedStorageCustomDictionary;

Adding words to the dictionary using the SpellCheck form saves them to the CustomDictionary.txt file created by the isolated storage. However, the words loaded in memory are not being updated.

Currently they can be updated by invoking the following method with reflection:

dict.GetType().GetMethod("ReadIsolatedStorage", BindingFlags.Instance | BindingFlags.NonPublic).Invoke(dict, null);



This method should be made public.