Public class modifier for WPF control

I'm creating Windows application and Class library. Class library contains WPF control named "InsertForm.xaml"

InsertForm contains TextBox na开发者_如何学Pythonmed eUserName.

I'm using the following code to show InsertForm. That's successful. But I can't access eUserName. How to set Textbox modifiers to public?

using System.Windows.Forms.Integration

ElementHost host = new ElementHost();
iform= new Extender.InsertForm();
host.Child = iform;
this.Controls.Add(host);

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Would this work?

<TextBox Name="eUserName" x:FieldModifier="public"/>