gui-utils:unsaved-warning

This displays a dialog that warns the user of a unsaved file.

• (gui-utils:unsaved-warning filename action can-save-now? parent) -> (union 'continue 'save 'cancel)
      filename : string
      action : string
      can-save-now? = #f : boolean
      parent = #f : (union #f (instance frame%) (instance dialog%))

  The string, action, indicates what action is about to take place. For example, if the application is about to close a file, a good action is "Close". The result symbol indicates the user's choice. If can-save-now? is #f, this function does not give the user the ``Save'' option and thus will not return 'save.