Is there any event to show the custom dialog while clicking a button in Connect Edition Ribbon ?

We have customized the ribbon by adding a new button into the ribbon tab. Now we want to connect our custom dialog created using MFC to it. 

Is there any API for getting the event while clicking that button ?

In the above screenshot the status and About are the buttons which were added and we need event while clicking the same..

Thanks,

Rama. Shrinivasan