Hi,
I succeded in solving my problem:
As rtf formatting is prior over the richtextbox one, I couldn't use it (at least as I could have noticed).
I solved my problem using
XamlPackage which gave me no problems at all while xaml gave me strange problems with
So the solution I've used is
I used this code to save content
TextRange t = new TextRange(this.MyRichTextBox.Document.ContentStart, this.MyRichtextbox.document.contentend);
FileStream fs = new FileStream (MyPath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
t.Save(fs, DataFormats.XamlPackage)
Fs.close()
And this to load
TextRange t = new TextRange(this.MyRichTextBox.Document.ContentStart, this.MyRichtextbox.document.contentend);
FileStream fs = new FileStream (MyPath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
t.Load(fs, DataFormats.XamlPackage)
Fs.close()