How to draw wavy line under a incorrect Persian word?

[Siamak]

I'm working on a project about Persian spell checker in the C# language. I have googled it and found some alternatives, but non of them draw "Wavy line" under misspelled words. for example I try to use Telerik RadRichTextBox and set my Application's Culture to "fa-IR" then load Persian Dictionary but It draw "Wavy Line" under any word (even correct English words) Except Persian Word. So I want to know, How can I draw wavy line under a certain word?

[Vasil]

Hi Siamak,

Thank you for your question.

First of all, we would like to mention that RadRichTextBox could use only one dictionary at a time for spell checking. You could find more information here.

Currently, RadRichTextBox doesn't allow spell checking in languages such as Persian, Hebrew and a few others, because they are interpreted as languages containing only upper case letters. Therefore, Persian text in your document is not marked with wavy line. 

Fortunately, for the upcoming 2012 Q3 release expected next month we will add a property which will allow spell checking of words with only upper letters, which means that it could be used for spell checking Persian and similar language.

Another thing to mention is that our spell checking algorithm is developed mainly for left to right languages and may cause different behavior for right to left language. Our initial tests over it demonstrates satisfying results, so we are optimistic for the spell checking of the right to left languages.

I hope this information was helpful.

Kind regards,
Vasil
the Telerik team