WPF Richtextbox Bindable in .net 4.5 - wpf

Question

So I'm trying to use David Veeneman's Bindable WPF RichTextBox here in my .net 4.5 project. After adding the control and the ValueConverter in my code I noticed only the the public object Convert() will be triggered but the public object ConvertBack() not.
After reading the comments to this project I changed following parts of the control source code.
private static void OnDocumentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var thisControl = (EcoRichTextBox)d;
if (thisControl.m_InternalUpdatePending > 0)
{
thisControl.m_InternalUpdatePending--;
return;
}
// Changed:
try
{
thisControl.TextBox.Document = (e.NewValue == null) ? new FlowDocument() : (FlowDocument)e.NewValue;
}
catch { }
thisControl.m_TextHasChanged = false;
}
And this Event Handler:
private void OnTextChanged(object sender, TextChangedEventArgs e)
{
// Set the TextChanged flag
m_TextHasChanged = true;
// Changed:
Document = TextBox.Document;
}
Now the the both method of the ValueConverter worked fine but events like private void OnNormalTextClick(object sender, RoutedEventArgs e) causes a FatalExecutionEngineError on Runtime.
So i wonder if there are major changes form WPF 3.5 to 4.5?
Or anybody have an idea to work around this?
Update
Binding in XAML
<uc:FsRichTextBox Margin="5"
Document="{Binding Path=Ereignis.Bericht,
Converter={StaticResource flowDocumentConverter},
UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True}" />

Answer 1

I ran the demo you linked here in VS2015 with target framework 4.0 and 4.5. It will not update when I take out the two way data binding.
Add to your RTB. Two way data binding and a name:
Mode=TwoWay
x:Name="EditBox"
I think rather than managing the text change yourself here, remove this:
// Changed:
Document = TextBox.Document;
Use an event handler to update the data.
Then in your event handler that is managing your updates (I am assuming a button click? And allow this to manage the update.
this.EditBox.UpdateDocumentBindings();
The x:name attribute is valuable.
This is all found in the source code.
If you can be more clear about how your project is arranged I can provide more detail. But for starters, I would do this. Stick more closely to the provided example.