Changing the string format of the WPF DatePicker

Question

I need to change the string format of the DatePickerTextBox in the WPF Toolkit DatePicker, to use hyphens instead of slashes for the seperators.

Is there a way to ov

Answer 1

The accepted answer (thanks @petrycol) put me on the right track, but I was getting another textbox border and background color within the actual date picker. Fixed it using the following code.