Handling unexpected response messages at a client-side application such as a web browser, where those responses require the client-side application to issue an unexpected prompt and are triggered by request messages sent from script executing in the client-side application. A widget is dynamically constructed to provide the prompt to a user. Display and processing of the widgets and prompts is handled in a non-disruptive manner in an environment where a gateway function requesting the prompt may be interposed between a browser and a server in a network, and where the browser script may adhere to the Ajax methodology.