ValidationTooltip auto-display on GotFocus

[Ian]

When an input field is in error I'd like to have the error (ValidationTooltip) display as soon as the user tabs into the field that's in error (GotFocus event), instead of having to move the mouse over the rather small triangle that's displayed when the parent control is in its "Invalid" state.

Is there an easy way to do this? I was hoping to be able to fire VisualStateManager.GoToState to trigger "InvalidFocused" state, but that doesn't appear to work.

Any suggestions as to how best to implement this?

Thanks