How to prevent wizard from closing

In fact, i try to use a similar way as explained here : https://www.reddit.com/r/javahelp/comments/39ogiw/cannot_prevent_javafx_dialog_from_closing/
Sadly, the dialog attribute of wizard is not visible, so i can call setOnCloseRequest;
Is there any proper way to do that ?

The main point is to only allow cancel and finish button to close the wizard.
This way, if during the wizard there is any huge background task working, the front part doesn't disapear on its own (i can disabele the previous/netx/finish button during the backgroud processing, but i didn't find a way to prevent closure).