Draging the connector to the canvas creates the form with data, can not be undoable (only delete from Outline and create again, but what happens with generated classes is unclear, they will remain same or can be regenerated but partially deleted or so...)
In praxis was interesting to create the AJAX driven portlet page when only 2 out of 3 portlets are refreshed.
Otherwise in common case the whole portlets page is reloaded which can cause too many useless calls to DB or what ever is behind.
The AJAX-bases reload of only needed Portlets is something not standard and requires not only ajax-bases CAF components but also some client-side java scripting (with this "defaultForm:..." etc. hard coded references).