How to notify the Collection widget from it's inner mashup ?

Hi, 

I use Collection to display a list of items ,  each item has a Delete button as following.  If delete one of the items,  I need to refresh the Collection  so that only display 2 items. 

But how can I notify the collection to be refreshed from it's inner/contained mashup ?   I didn't found any event or mashup parameters can be used for this . 

Session parameter may solve it, but is there a elegant solution ? 

__________ _________ _________ 
| | | | | |
| Delete | | Delete | |Delete |
|________| |________| |________|

Regards,

Sean