Update TextBox in a page displayed inside a frame from a ribbon

Question

I have a wpf application with a ribbon. I want to change Textboxes from another page displayed inside a frame under my ribbon. And I want to do it from a RibbonButton. Is it possible?

Answer 1

 ((Page1)frame1.Content).TextBox1.Text = "Hello, World";

But it's best to use a class, and binding the textbox.