Passing data from a textbox on wpf control (element host) to a Winform form

[VintageCoro]

Hey Everyone

I have a VB.net project (.Net framework 4.0), with a number of forms. One of the the forms is called (AddModel.vb) where a user of this application can add a model file (e.g. MD5, OBJ, 3DS). On this form there is a Element host that is used to display a WPF Control called (SpellCheckTextbox.xaml). The WPF Control only contains a rich textbox with the ability to spell check the contents of itself. I want to be able to pass the contents of the WPF Rich textbox to a String in either the AddModel.vb form or a module, so that when I click the "Ok" button on my AddModel form, the text is added to a record in my database. However everything I've tried to get the wpf Rich textbox contents and pass it to a public string somewhere else in my application as failed.

Thank you for reading