Configurable prompt dialog box on form submission

In Leap form workflow, you can set form submission settings "upon submission". It should optionally be possible to define a messagebox that is shown on submission. A typical message box for submission would be a yes/no box with customizable text e.g. "Are you really sure, you want to save the document? Yes/No". There is no built-in function for promting a dialog with yes/no/cancel options. There is only the function app.showMessage() where we can show a Dialog with only an OK button. We need a functionality for showing a configurable prompt, similar to that in LotusScript ( https://help.hcltechsw.com/dom_designer/10.0.1/basic/H_PROMPT_METHOD_7966_ABOUT.html ). That way we can call a prompt within validateButtonPressed and after that respond with true or false, either which was selected in the prompt.