Here is an image to help clarify my question.
Three TextBoxes and a TextBlock. I want the TextBlock to mirror the contents of one TextBox, but, if I mouse over another TextBox the TextBlock will mirror the Text of that TextBox instead. Mousing over a TextBox is just an arbitrary way to choose one TextBox over another. I have one requirement though and that is that the TextBlock be bound to a VM property and never directly to the Text property of a TextBox.
Any help appreciated,