XPSendMessageToWidget

WIDGET_API int        XPSendMessageToWidget(
                         XPWidgetID           inWidget,    
                         XPWidgetMessage      inMessage,    
                         XPDispatchMode       inMode,    
                         intptr_t             inParam1,    
                         intptr_t             inParam2);    

This sends any message to a widget. You should probably not go around simulating the predefined messages that the widgets library defines for you. You may however define custom messages for your widgets and send them with this method.

This method supports several dispatching patterns; see XPDispatchMode for more info. The function returns 1 if the message was handled, 0 if it was not.

For each widget that receives the message (see the dispatching modes), each widget function from the most recently installed to the oldest one receives the message in order until it is handled.