lButtonDown( <nRow>, <nCol>, nFlags> -> <nil>      
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   This Method is called when the left MouseButton is pressed over our 
   messagebar ( iE the message bar receives a WM_LBUTTONDOWN message )
   It checks which message bar item is hit and sends this a ::Click()
   message, which will in turn will evaluate the bAction codeblock.

   please press  Related Topics:  and select  WM_BUTTON  for
   detailed informations about the topic and parameters