MirrorTextField

Hi,
I was wondering what is the purpose of the MirrorTextField?
And is it possible to provide some samples or detailed documentation, different than the one coming with the SDK "This control is used for inserting/editing/viewing simple text with the built in option to mirror the value of another text field."

I tried using it in a Form template but was not able to make it mirror the value of another TextField control. Is this the purpose of the control and how can this happen?

Thanks!