,-----.                                                    
      |start|                                                    
      |-----|                                                    
      `-----'                                                    
         |                                                       
         |                                                       
,-----------------.  ,---------------------.                     
|{{               |  |{{                   |   ,----------------.
|-----------------|  |---------------------|   |{{              |
|{+               |  |{+                   |   |----------------|
|<b>an example    |  |<b>please wait       |   |{+              |
|choose one option|  |operation in progress|   |<b>success      |
|()one            |--|<&clock>             |---|congratulations!|
|()two            |  |[cancel]             |   |[ok]            |
|[ok]             |  |}                    |   |}               |
|}                |  |}}                   |   |}}              |
|}}               |  |                     |   |                |
|                 |  `---------------------'   `----------------'
`-----------------'              |                               
                                 |                               
                         ,-------------.                         
                         |{{           |                         
                         |-------------|                         
                         |{+           |                         
                         |<b>error     |                         
                         |failed, sorry|                         
                         |[ok]         |                         
                         |}            |                         
                         |}}           |                         
                         |             |                         
                         `-------------'