OnPostClick is generated after the code of the OnClick event handler has been called. If Wait is true when the media player was clicked, OnPostClick won't be called until the completion of the OnClick code. If Wait is false, control can return to the application before completion of the OnClick code; therefore, the OnPostClick event may occur before the actions initiated by the OnClick event have completed. 

For example, if the user clicks the Play button and the DoDefault parameter of the OnClick event handler for the media player is true, the media is played. If the media is long enough, it will still be playing when the OnPostClick event is generated if Wait is true. If Wait is false, however, OnPostClick won't occur until the media has finished playing. 

OnClick 

PostClick 

Wait