What I have done now is to enable the back/next button whenever there is a previous/next step. There is an override available where you can specify

canGoNext

and

canGoBack

as a

BooleanExpression

if you want another behavior. Same goes for

Finish

. By default, it is always available, but you can override

canFinish

and create some binding or property which you update based on the input. This gives the flexibility to only enable buttons when they can actually do something meaningful, but we don't require the author of the Wizard to create a water tight scheme for the button states.