Inviting Internet connection setup in browsers, mailers, and IM clients

If you are not connected to the Internet, Ubuntu's default Web browser, mailer, and IM client should explain this in plain language, and lead you towards setting up an Internet connection.

In this situation, Firefox currently says "Firefox is currently in offline mode and can't browse the Web". It asks if you are connected to a network, as if it doesn't know; and suggests that you "Place the browser in online mode" and try again, which never works. Evolution quietly complains "Error while Refreshing folder" [sic], and similarly gives no hint of how you can solve the problem. And Pidgin pretends you are "Available" when you are not online. Epiphany, Thunderbird, and Empathy are similarly unhelpful.