[news.eclipse.platform] A question about model-control-view.

["Michael" <my25@xxxxxxxxxxxxx>]

Hi,
    If we contribute an action to popup menu using the extension point: 
org.eclipse.ui.popupMenus, we can define an objectContribution. Then, the 
Eclipse know how to configure the popup menu based on type of object that is 
a model of the right-clicked UI elment.  What I am wandering is how Eclipse 
know the mapping from the chosed UI element to the underlying model of this 
object. I really don't know what part eclipse API handle this mechinism. Do 
you have any idea about this?
     Thanks.
Best regards.
Michael.