\button{\symbol[StartRendering]} [StartRendering{#1}]\enspace
       \button{\symbol[StopRendering]}  [StopRendering{#1}]\enspace
       \button{\symbol[PauseRendering]} [PauseRendering{#1}]\enspace
       \button{\symbol[ResumeRendering]}[ResumeRendering{#1}]}}

The above statements used to produce buttons for start/stop playing, etc. Like: