Is there any easy way to implement simple dialog boxes, for instance requiring a user to answer a question YES or NO? I tried composing something in Mendix using a YesNoResponse object and displaying it in a modal popup form, but got quite tied up in knots. Alternatively is it possible to use things like JOptionPanes inside Java actions?
You might want to take a look at the answer to this question, which describes how to achieve a dialog box to obtain user input.
Using a JOptionPane or similar is not an option as this will pop up a dialog box on the server instead of the client.