[Click handler action] If the DefaultPlaybackRate is not 1.0, sets the DefaultPlaybackRate to 1.0. The handler then calls the Playmethod. [Button] 
Play
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P a u s e
F a s t f o r w a r d
R e w i n d
P l a y
M u t e
V o l u m e u p , V o l u m e d o w n